diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-rk3x.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-rk3x.c | 1411 |
1 files changed, 1411 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c new file mode 100644 index 000000000..4362db7c5 --- /dev/null +++ b/drivers/i2c/busses/i2c-rk3x.c @@ -0,0 +1,1411 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for I2C adapter in Rockchip RK3xxx SoC + * + * Max Schwarz <max.schwarz@online.de> + * based on the patches by Rockchip Inc. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/iopoll.h> +#include <linux/errno.h> +#include <linux/err.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/spinlock.h> +#include <linux/clk.h> +#include <linux/wait.h> +#include <linux/mfd/syscon.h> +#include <linux/regmap.h> +#include <linux/math64.h> + + +/* Register Map */ +#define REG_CON 0x00 /* control register */ +#define REG_CLKDIV 0x04 /* clock divisor register */ +#define REG_MRXADDR 0x08 /* slave address for REGISTER_TX */ +#define REG_MRXRADDR 0x0c /* slave register address for REGISTER_TX */ +#define REG_MTXCNT 0x10 /* number of bytes to be transmitted */ +#define REG_MRXCNT 0x14 /* number of bytes to be received */ +#define REG_IEN 0x18 /* interrupt enable */ +#define REG_IPD 0x1c /* interrupt pending */ +#define REG_FCNT 0x20 /* finished count */ + +/* Data buffer offsets */ +#define TXBUFFER_BASE 0x100 +#define RXBUFFER_BASE 0x200 + +/* REG_CON bits */ +#define REG_CON_EN BIT(0) +enum { + REG_CON_MOD_TX = 0, /* transmit data */ + REG_CON_MOD_REGISTER_TX, /* select register and restart */ + REG_CON_MOD_RX, /* receive data */ + REG_CON_MOD_REGISTER_RX, /* broken: transmits read addr AND writes + * register addr */ +}; +#define REG_CON_MOD(mod) ((mod) << 1) +#define REG_CON_MOD_MASK (BIT(1) | BIT(2)) +#define REG_CON_START BIT(3) +#define REG_CON_STOP BIT(4) +#define REG_CON_LASTACK BIT(5) /* 1: send NACK after last received byte */ +#define REG_CON_ACTACK BIT(6) /* 1: stop if NACK is received */ + +#define REG_CON_TUNING_MASK GENMASK_ULL(15, 8) + +#define REG_CON_SDA_CFG(cfg) ((cfg) << 8) +#define REG_CON_STA_CFG(cfg) ((cfg) << 12) +#define REG_CON_STO_CFG(cfg) ((cfg) << 14) + +/* REG_MRXADDR bits */ +#define REG_MRXADDR_VALID(x) BIT(24 + (x)) /* [x*8+7:x*8] of MRX[R]ADDR valid */ + +/* REG_IEN/REG_IPD bits */ +#define REG_INT_BTF BIT(0) /* a byte was transmitted */ +#define REG_INT_BRF BIT(1) /* a byte was received */ +#define REG_INT_MBTF BIT(2) /* master data transmit finished */ +#define REG_INT_MBRF BIT(3) /* master data receive finished */ +#define REG_INT_START BIT(4) /* START condition generated */ +#define REG_INT_STOP BIT(5) /* STOP condition generated */ +#define REG_INT_NAKRCV BIT(6) /* NACK received */ +#define REG_INT_ALL 0x7f + +/* Constants */ +#define WAIT_TIMEOUT 1000 /* ms */ +#define DEFAULT_SCL_RATE (100 * 1000) /* Hz */ + +/** + * struct i2c_spec_values - I2C specification values for various modes + * @min_hold_start_ns: min hold time (repeated) START condition + * @min_low_ns: min LOW period of the SCL clock + * @min_high_ns: min HIGH period of the SCL cloc + * @min_setup_start_ns: min set-up time for a repeated START conditio + * @max_data_hold_ns: max data hold time + * @min_data_setup_ns: min data set-up time + * @min_setup_stop_ns: min set-up time for STOP condition + * @min_hold_buffer_ns: min bus free time between a STOP and + * START condition + */ +struct i2c_spec_values { + unsigned long min_hold_start_ns; + unsigned long min_low_ns; + unsigned long min_high_ns; + unsigned long min_setup_start_ns; + unsigned long max_data_hold_ns; + unsigned long min_data_setup_ns; + unsigned long min_setup_stop_ns; + unsigned long min_hold_buffer_ns; +}; + +static const struct i2c_spec_values standard_mode_spec = { + .min_hold_start_ns = 4000, + .min_low_ns = 4700, + .min_high_ns = 4000, + .min_setup_start_ns = 4700, + .max_data_hold_ns = 3450, + .min_data_setup_ns = 250, + .min_setup_stop_ns = 4000, + .min_hold_buffer_ns = 4700, +}; + +static const struct i2c_spec_values fast_mode_spec = { + .min_hold_start_ns = 600, + .min_low_ns = 1300, + .min_high_ns = 600, + .min_setup_start_ns = 600, + .max_data_hold_ns = 900, + .min_data_setup_ns = 100, + .min_setup_stop_ns = 600, + .min_hold_buffer_ns = 1300, +}; + +static const struct i2c_spec_values fast_mode_plus_spec = { + .min_hold_start_ns = 260, + .min_low_ns = 500, + .min_high_ns = 260, + .min_setup_start_ns = 260, + .max_data_hold_ns = 400, + .min_data_setup_ns = 50, + .min_setup_stop_ns = 260, + .min_hold_buffer_ns = 500, +}; + +/** + * struct rk3x_i2c_calced_timings - calculated V1 timings + * @div_low: Divider output for low + * @div_high: Divider output for high + * @tuning: Used to adjust setup/hold data time, + * setup/hold start time and setup stop time for + * v1's calc_timings, the tuning should all be 0 + * for old hardware anyone using v0's calc_timings. + */ +struct rk3x_i2c_calced_timings { + unsigned long div_low; + unsigned long div_high; + unsigned int tuning; +}; + +enum rk3x_i2c_state { + STATE_IDLE, + STATE_START, + STATE_READ, + STATE_WRITE, + STATE_STOP +}; + +/** + * struct rk3x_i2c_soc_data - SOC-specific data + * @grf_offset: offset inside the grf regmap for setting the i2c type + * @calc_timings: Callback function for i2c timing information calculated + */ +struct rk3x_i2c_soc_data { + int grf_offset; + int (*calc_timings)(unsigned long, struct i2c_timings *, + struct rk3x_i2c_calced_timings *); +}; + +/** + * struct rk3x_i2c - private data of the controller + * @adap: corresponding I2C adapter + * @dev: device for this controller + * @soc_data: related soc data struct + * @regs: virtual memory area + * @clk: function clk for rk3399 or function & Bus clks for others + * @pclk: Bus clk for rk3399 + * @clk_rate_nb: i2c clk rate change notify + * @irq: irq number + * @t: I2C known timing information + * @lock: spinlock for the i2c bus + * @wait: the waitqueue to wait for i2c transfer + * @busy: the condition for the event to wait for + * @msg: current i2c message + * @addr: addr of i2c slave device + * @mode: mode of i2c transfer + * @is_last_msg: flag determines whether it is the last msg in this transfer + * @state: state of i2c transfer + * @processed: byte length which has been send or received + * @error: error code for i2c transfer + */ +struct rk3x_i2c { + struct i2c_adapter adap; + struct device *dev; + const struct rk3x_i2c_soc_data *soc_data; + + /* Hardware resources */ + void __iomem *regs; + struct clk *clk; + struct clk *pclk; + struct notifier_block clk_rate_nb; + int irq; + + /* Settings */ + struct i2c_timings t; + + /* Synchronization & notification */ + spinlock_t lock; + wait_queue_head_t wait; + bool busy; + + /* Current message */ + struct i2c_msg *msg; + u8 addr; + unsigned int mode; + bool is_last_msg; + + /* I2C state machine */ + enum rk3x_i2c_state state; + unsigned int processed; + int error; +}; + +static inline void i2c_writel(struct rk3x_i2c *i2c, u32 value, + unsigned int offset) +{ + writel(value, i2c->regs + offset); +} + +static inline u32 i2c_readl(struct rk3x_i2c *i2c, unsigned int offset) +{ + return readl(i2c->regs + offset); +} + +/* Reset all interrupt pending bits */ +static inline void rk3x_i2c_clean_ipd(struct rk3x_i2c *i2c) +{ + i2c_writel(i2c, REG_INT_ALL, REG_IPD); +} + +/** + * rk3x_i2c_start - Generate a START condition, which triggers a REG_INT_START interrupt. + * @i2c: target controller data + */ +static void rk3x_i2c_start(struct rk3x_i2c *i2c) +{ + u32 val = i2c_readl(i2c, REG_CON) & REG_CON_TUNING_MASK; + + i2c_writel(i2c, REG_INT_START, REG_IEN); + + /* enable adapter with correct mode, send START condition */ + val |= REG_CON_EN | REG_CON_MOD(i2c->mode) | REG_CON_START; + + /* if we want to react to NACK, set ACTACK bit */ + if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) + val |= REG_CON_ACTACK; + + i2c_writel(i2c, val, REG_CON); +} + +/** + * rk3x_i2c_stop - Generate a STOP condition, which triggers a REG_INT_STOP interrupt. + * @i2c: target controller data + * @error: Error code to return in rk3x_i2c_xfer + */ +static void rk3x_i2c_stop(struct rk3x_i2c *i2c, int error) +{ + unsigned int ctrl; + + i2c->processed = 0; + i2c->msg = NULL; + i2c->error = error; + + if (i2c->is_last_msg) { + /* Enable stop interrupt */ + i2c_writel(i2c, REG_INT_STOP, REG_IEN); + + i2c->state = STATE_STOP; + + ctrl = i2c_readl(i2c, REG_CON); + ctrl |= REG_CON_STOP; + i2c_writel(i2c, ctrl, REG_CON); + } else { + /* Signal rk3x_i2c_xfer to start the next message. */ + i2c->busy = false; + i2c->state = STATE_IDLE; + + /* + * The HW is actually not capable of REPEATED START. But we can + * get the intended effect by resetting its internal state + * and issuing an ordinary START. + */ + ctrl = i2c_readl(i2c, REG_CON) & REG_CON_TUNING_MASK; + i2c_writel(i2c, ctrl, REG_CON); + + /* signal that we are finished with the current msg */ + wake_up(&i2c->wait); + } +} + +/** + * rk3x_i2c_prepare_read - Setup a read according to i2c->msg + * @i2c: target controller data + */ +static void rk3x_i2c_prepare_read(struct rk3x_i2c *i2c) +{ + unsigned int len = i2c->msg->len - i2c->processed; + u32 con; + + con = i2c_readl(i2c, REG_CON); + + /* + * The hw can read up to 32 bytes at a time. If we need more than one + * chunk, send an ACK after the last byte of the current chunk. + */ + if (len > 32) { + len = 32; + con &= ~REG_CON_LASTACK; + } else { + con |= REG_CON_LASTACK; + } + + /* make sure we are in plain RX mode if we read a second chunk */ + if (i2c->processed != 0) { + con &= ~REG_CON_MOD_MASK; + con |= REG_CON_MOD(REG_CON_MOD_RX); + } + + i2c_writel(i2c, con, REG_CON); + i2c_writel(i2c, len, REG_MRXCNT); +} + +/** + * rk3x_i2c_fill_transmit_buf - Fill the transmit buffer with data from i2c->msg + * @i2c: target controller data + */ +static void rk3x_i2c_fill_transmit_buf(struct rk3x_i2c *i2c) +{ + unsigned int i, j; + u32 cnt = 0; + u32 val; + u8 byte; + + for (i = 0; i < 8; ++i) { + val = 0; + for (j = 0; j < 4; ++j) { + if ((i2c->processed == i2c->msg->len) && (cnt != 0)) + break; + + if (i2c->processed == 0 && cnt == 0) + byte = (i2c->addr & 0x7f) << 1; + else + byte = i2c->msg->buf[i2c->processed++]; + + val |= byte << (j * 8); + cnt++; + } + + i2c_writel(i2c, val, TXBUFFER_BASE + 4 * i); + + if (i2c->processed == i2c->msg->len) + break; + } + + i2c_writel(i2c, cnt, REG_MTXCNT); +} + + +/* IRQ handlers for individual states */ + +static void rk3x_i2c_handle_start(struct rk3x_i2c *i2c, unsigned int ipd) +{ + if (!(ipd & REG_INT_START)) { + rk3x_i2c_stop(i2c, -EIO); + dev_warn(i2c->dev, "unexpected irq in START: 0x%x\n", ipd); + rk3x_i2c_clean_ipd(i2c); + return; + } + + /* ack interrupt */ + i2c_writel(i2c, REG_INT_START, REG_IPD); + + /* disable start bit */ + i2c_writel(i2c, i2c_readl(i2c, REG_CON) & ~REG_CON_START, REG_CON); + + /* enable appropriate interrupts and transition */ + if (i2c->mode == REG_CON_MOD_TX) { + i2c_writel(i2c, REG_INT_MBTF | REG_INT_NAKRCV, REG_IEN); + i2c->state = STATE_WRITE; + rk3x_i2c_fill_transmit_buf(i2c); + } else { + /* in any other case, we are going to be reading. */ + i2c_writel(i2c, REG_INT_MBRF | REG_INT_NAKRCV, REG_IEN); + i2c->state = STATE_READ; + rk3x_i2c_prepare_read(i2c); + } +} + +static void rk3x_i2c_handle_write(struct rk3x_i2c *i2c, unsigned int ipd) +{ + if (!(ipd & REG_INT_MBTF)) { + rk3x_i2c_stop(i2c, -EIO); + dev_err(i2c->dev, "unexpected irq in WRITE: 0x%x\n", ipd); + rk3x_i2c_clean_ipd(i2c); + return; + } + + /* ack interrupt */ + i2c_writel(i2c, REG_INT_MBTF, REG_IPD); + + /* are we finished? */ + if (i2c->processed == i2c->msg->len) + rk3x_i2c_stop(i2c, i2c->error); + else + rk3x_i2c_fill_transmit_buf(i2c); +} + +static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd) +{ + unsigned int i; + unsigned int len = i2c->msg->len - i2c->processed; + u32 val; + u8 byte; + + /* we only care for MBRF here. */ + if (!(ipd & REG_INT_MBRF)) + return; + + /* ack interrupt (read also produces a spurious START flag, clear it too) */ + i2c_writel(i2c, REG_INT_MBRF | REG_INT_START, REG_IPD); + + /* Can only handle a maximum of 32 bytes at a time */ + if (len > 32) + len = 32; + + /* read the data from receive buffer */ + for (i = 0; i < len; ++i) { + if (i % 4 == 0) + val = i2c_readl(i2c, RXBUFFER_BASE + (i / 4) * 4); + + byte = (val >> ((i % 4) * 8)) & 0xff; + i2c->msg->buf[i2c->processed++] = byte; + } + + /* are we finished? */ + if (i2c->processed == i2c->msg->len) + rk3x_i2c_stop(i2c, i2c->error); + else + rk3x_i2c_prepare_read(i2c); +} + +static void rk3x_i2c_handle_stop(struct rk3x_i2c *i2c, unsigned int ipd) +{ + unsigned int con; + + if (!(ipd & REG_INT_STOP)) { + rk3x_i2c_stop(i2c, -EIO); + dev_err(i2c->dev, "unexpected irq in STOP: 0x%x\n", ipd); + rk3x_i2c_clean_ipd(i2c); + return; + } + + /* ack interrupt */ + i2c_writel(i2c, REG_INT_STOP, REG_IPD); + + /* disable STOP bit */ + con = i2c_readl(i2c, REG_CON); + con &= ~REG_CON_STOP; + i2c_writel(i2c, con, REG_CON); + + i2c->busy = false; + i2c->state = STATE_IDLE; + + /* signal rk3x_i2c_xfer that we are finished */ + wake_up(&i2c->wait); +} + +static irqreturn_t rk3x_i2c_irq(int irqno, void *dev_id) +{ + struct rk3x_i2c *i2c = dev_id; + unsigned int ipd; + + spin_lock(&i2c->lock); + + ipd = i2c_readl(i2c, REG_IPD); + if (i2c->state == STATE_IDLE) { + dev_warn(i2c->dev, "irq in STATE_IDLE, ipd = 0x%x\n", ipd); + rk3x_i2c_clean_ipd(i2c); + goto out; + } + + dev_dbg(i2c->dev, "IRQ: state %d, ipd: %x\n", i2c->state, ipd); + + /* Clean interrupt bits we don't care about */ + ipd &= ~(REG_INT_BRF | REG_INT_BTF); + + if (ipd & REG_INT_NAKRCV) { + /* + * We got a NACK in the last operation. Depending on whether + * IGNORE_NAK is set, we have to stop the operation and report + * an error. + */ + i2c_writel(i2c, REG_INT_NAKRCV, REG_IPD); + + ipd &= ~REG_INT_NAKRCV; + + if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) + rk3x_i2c_stop(i2c, -ENXIO); + } + + /* is there anything left to handle? */ + if ((ipd & REG_INT_ALL) == 0) + goto out; + + switch (i2c->state) { + case STATE_START: + rk3x_i2c_handle_start(i2c, ipd); + break; + case STATE_WRITE: + rk3x_i2c_handle_write(i2c, ipd); + break; + case STATE_READ: + rk3x_i2c_handle_read(i2c, ipd); + break; + case STATE_STOP: + rk3x_i2c_handle_stop(i2c, ipd); + break; + case STATE_IDLE: + break; + } + +out: + spin_unlock(&i2c->lock); + return IRQ_HANDLED; +} + +/** + * rk3x_i2c_get_spec - Get timing values of I2C specification + * @speed: Desired SCL frequency + * + * Return: Matched i2c_spec_values. + */ +static const struct i2c_spec_values *rk3x_i2c_get_spec(unsigned int speed) +{ + if (speed <= I2C_MAX_STANDARD_MODE_FREQ) + return &standard_mode_spec; + else if (speed <= I2C_MAX_FAST_MODE_FREQ) + return &fast_mode_spec; + else + return &fast_mode_plus_spec; +} + +/** + * rk3x_i2c_v0_calc_timings - Calculate divider values for desired SCL frequency + * @clk_rate: I2C input clock rate + * @t: Known I2C timing information + * @t_calc: Caculated rk3x private timings that would be written into regs + * + * Return: %0 on success, -%EINVAL if the goal SCL rate is too slow. In that case + * a best-effort divider value is returned in divs. If the target rate is + * too high, we silently use the highest possible rate. + */ +static int rk3x_i2c_v0_calc_timings(unsigned long clk_rate, + struct i2c_timings *t, + struct rk3x_i2c_calced_timings *t_calc) +{ + unsigned long min_low_ns, min_high_ns; + unsigned long max_low_ns, min_total_ns; + + unsigned long clk_rate_khz, scl_rate_khz; + + unsigned long min_low_div, min_high_div; + unsigned long max_low_div; + + unsigned long min_div_for_hold, min_total_div; + unsigned long extra_div, extra_low_div, ideal_low_div; + + unsigned long data_hold_buffer_ns = 50; + const struct i2c_spec_values *spec; + int ret = 0; + + /* Only support standard-mode and fast-mode */ + if (WARN_ON(t->bus_freq_hz > I2C_MAX_FAST_MODE_FREQ)) + t->bus_freq_hz = I2C_MAX_FAST_MODE_FREQ; + + /* prevent scl_rate_khz from becoming 0 */ + if (WARN_ON(t->bus_freq_hz < 1000)) + t->bus_freq_hz = 1000; + + /* + * min_low_ns: The minimum number of ns we need to hold low to + * meet I2C specification, should include fall time. + * min_high_ns: The minimum number of ns we need to hold high to + * meet I2C specification, should include rise time. + * max_low_ns: The maximum number of ns we can hold low to meet + * I2C specification. + * + * Note: max_low_ns should be (maximum data hold time * 2 - buffer) + * This is because the i2c host on Rockchip holds the data line + * for half the low time. + */ + spec = rk3x_i2c_get_spec(t->bus_freq_hz); + min_high_ns = t->scl_rise_ns + spec->min_high_ns; + + /* + * Timings for repeated start: + * - controller appears to drop SDA at .875x (7/8) programmed clk high. + * - controller appears to keep SCL high for 2x programmed clk high. + * + * We need to account for those rules in picking our "high" time so + * we meet tSU;STA and tHD;STA times. + */ + min_high_ns = max(min_high_ns, DIV_ROUND_UP( + (t->scl_rise_ns + spec->min_setup_start_ns) * 1000, 875)); + min_high_ns = max(min_high_ns, DIV_ROUND_UP( + (t->scl_rise_ns + spec->min_setup_start_ns + t->sda_fall_ns + + spec->min_high_ns), 2)); + + min_low_ns = t->scl_fall_ns + spec->min_low_ns; + max_low_ns = spec->max_data_hold_ns * 2 - data_hold_buffer_ns; + min_total_ns = min_low_ns + min_high_ns; + + /* Adjust to avoid overflow */ + clk_rate_khz = DIV_ROUND_UP(clk_rate, 1000); + scl_rate_khz = t->bus_freq_hz / 1000; + + /* + * We need the total div to be >= this number + * so we don't clock too fast. + */ + min_total_div = DIV_ROUND_UP(clk_rate_khz, scl_rate_khz * 8); + + /* These are the min dividers needed for min hold times. */ + min_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns, 8 * 1000000); + min_high_div = DIV_ROUND_UP(clk_rate_khz * min_high_ns, 8 * 1000000); + min_div_for_hold = (min_low_div + min_high_div); + + /* + * This is the maximum divider so we don't go over the maximum. + * We don't round up here (we round down) since this is a maximum. + */ + max_low_div = clk_rate_khz * max_low_ns / (8 * 1000000); + + if (min_low_div > max_low_div) { + WARN_ONCE(true, + "Conflicting, min_low_div %lu, max_low_div %lu\n", + min_low_div, max_low_div); + max_low_div = min_low_div; + } + + if (min_div_for_hold > min_total_div) { + /* + * Time needed to meet hold requirements is important. + * Just use that. + */ + t_calc->div_low = min_low_div; + t_calc->div_high = min_high_div; + } else { + /* + * We've got to distribute some time among the low and high + * so we don't run too fast. + */ + extra_div = min_total_div - min_div_for_hold; + + /* + * We'll try to split things up perfectly evenly, + * biasing slightly towards having a higher div + * for low (spend more time low). + */ + ideal_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns, + scl_rate_khz * 8 * min_total_ns); + + /* Don't allow it to go over the maximum */ + if (ideal_low_div > max_low_div) + ideal_low_div = max_low_div; + + /* + * Handle when the ideal low div is going to take up + * more than we have. + */ + if (ideal_low_div > min_low_div + extra_div) + ideal_low_div = min_low_div + extra_div; + + /* Give low the "ideal" and give high whatever extra is left */ + extra_low_div = ideal_low_div - min_low_div; + t_calc->div_low = ideal_low_div; + t_calc->div_high = min_high_div + (extra_div - extra_low_div); + } + + /* + * Adjust to the fact that the hardware has an implicit "+1". + * NOTE: Above calculations always produce div_low > 0 and div_high > 0. + */ + t_calc->div_low--; + t_calc->div_high--; + + /* Give the tuning value 0, that would not update con register */ + t_calc->tuning = 0; + /* Maximum divider supported by hw is 0xffff */ + if (t_calc->div_low > 0xffff) { + t_calc->div_low = 0xffff; + ret = -EINVAL; + } + + if (t_calc->div_high > 0xffff) { + t_calc->div_high = 0xffff; + ret = -EINVAL; + } + + return ret; +} + +/** + * rk3x_i2c_v1_calc_timings - Calculate timing values for desired SCL frequency + * @clk_rate: I2C input clock rate + * @t: Known I2C timing information + * @t_calc: Caculated rk3x private timings that would be written into regs + * + * Return: %0 on success, -%EINVAL if the goal SCL rate is too slow. In that case + * a best-effort divider value is returned in divs. If the target rate is + * too high, we silently use the highest possible rate. + * The following formulas are v1's method to calculate timings. + * + * l = divl + 1; + * h = divh + 1; + * s = sda_update_config + 1; + * u = start_setup_config + 1; + * p = stop_setup_config + 1; + * T = Tclk_i2c; + * + * tHigh = 8 * h * T; + * tLow = 8 * l * T; + * + * tHD;sda = (l * s + 1) * T; + * tSU;sda = [(8 - s) * l + 1] * T; + * tI2C = 8 * (l + h) * T; + * + * tSU;sta = (8h * u + 1) * T; + * tHD;sta = [8h * (u + 1) - 1] * T; + * tSU;sto = (8h * p + 1) * T; + */ +static int rk3x_i2c_v1_calc_timings(unsigned long clk_rate, + struct i2c_timings *t, + struct rk3x_i2c_calced_timings *t_calc) +{ + unsigned long min_low_ns, min_high_ns; + unsigned long min_setup_start_ns, min_setup_data_ns; + unsigned long min_setup_stop_ns, max_hold_data_ns; + + unsigned long clk_rate_khz, scl_rate_khz; + + unsigned long min_low_div, min_high_div; + + unsigned long min_div_for_hold, min_total_div; + unsigned long extra_div, extra_low_div; + unsigned long sda_update_cfg, stp_sta_cfg, stp_sto_cfg; + + const struct i2c_spec_values *spec; + int ret = 0; + + /* Support standard-mode, fast-mode and fast-mode plus */ + if (WARN_ON(t->bus_freq_hz > I2C_MAX_FAST_MODE_PLUS_FREQ)) + t->bus_freq_hz = I2C_MAX_FAST_MODE_PLUS_FREQ; + + /* prevent scl_rate_khz from becoming 0 */ + if (WARN_ON(t->bus_freq_hz < 1000)) + t->bus_freq_hz = 1000; + + /* + * min_low_ns: The minimum number of ns we need to hold low to + * meet I2C specification, should include fall time. + * min_high_ns: The minimum number of ns we need to hold high to + * meet I2C specification, should include rise time. + */ + spec = rk3x_i2c_get_spec(t->bus_freq_hz); + + /* calculate min-divh and min-divl */ + clk_rate_khz = DIV_ROUND_UP(clk_rate, 1000); + scl_rate_khz = t->bus_freq_hz / 1000; + min_total_div = DIV_ROUND_UP(clk_rate_khz, scl_rate_khz * 8); + + min_high_ns = t->scl_rise_ns + spec->min_high_ns; + min_high_div = DIV_ROUND_UP(clk_rate_khz * min_high_ns, 8 * 1000000); + + min_low_ns = t->scl_fall_ns + spec->min_low_ns; + min_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns, 8 * 1000000); + + /* + * Final divh and divl must be greater than 0, otherwise the + * hardware would not output the i2c clk. + */ + min_high_div = (min_high_div < 1) ? 2 : min_high_div; + min_low_div = (min_low_div < 1) ? 2 : min_low_div; + + /* These are the min dividers needed for min hold times. */ + min_div_for_hold = (min_low_div + min_high_div); + + /* + * This is the maximum divider so we don't go over the maximum. + * We don't round up here (we round down) since this is a maximum. + */ + if (min_div_for_hold >= min_total_div) { + /* + * Time needed to meet hold requirements is important. + * Just use that. + */ + t_calc->div_low = min_low_div; + t_calc->div_high = min_high_div; + } else { + /* + * We've got to distribute some time among the low and high + * so we don't run too fast. + * We'll try to split things up by the scale of min_low_div and + * min_high_div, biasing slightly towards having a higher div + * for low (spend more time low). + */ + extra_div = min_total_div - min_div_for_hold; + extra_low_div = DIV_ROUND_UP(min_low_div * extra_div, + min_div_for_hold); + + t_calc->div_low = min_low_div + extra_low_div; + t_calc->div_high = min_high_div + (extra_div - extra_low_div); + } + + /* + * calculate sda data hold count by the rules, data_upd_st:3 + * is a appropriate value to reduce calculated times. + */ + for (sda_update_cfg = 3; sda_update_cfg > 0; sda_update_cfg--) { + max_hold_data_ns = DIV_ROUND_UP((sda_update_cfg + * (t_calc->div_low) + 1) + * 1000000, clk_rate_khz); + min_setup_data_ns = DIV_ROUND_UP(((8 - sda_update_cfg) + * (t_calc->div_low) + 1) + * 1000000, clk_rate_khz); + if ((max_hold_data_ns < spec->max_data_hold_ns) && + (min_setup_data_ns > spec->min_data_setup_ns)) + break; + } + + /* calculate setup start config */ + min_setup_start_ns = t->scl_rise_ns + spec->min_setup_start_ns; + stp_sta_cfg = DIV_ROUND_UP(clk_rate_khz * min_setup_start_ns + - 1000000, 8 * 1000000 * (t_calc->div_high)); + + /* calculate setup stop config */ + min_setup_stop_ns = t->scl_rise_ns + spec->min_setup_stop_ns; + stp_sto_cfg = DIV_ROUND_UP(clk_rate_khz * min_setup_stop_ns + - 1000000, 8 * 1000000 * (t_calc->div_high)); + + t_calc->tuning = REG_CON_SDA_CFG(--sda_update_cfg) | + REG_CON_STA_CFG(--stp_sta_cfg) | + REG_CON_STO_CFG(--stp_sto_cfg); + + t_calc->div_low--; + t_calc->div_high--; + + /* Maximum divider supported by hw is 0xffff */ + if (t_calc->div_low > 0xffff) { + t_calc->div_low = 0xffff; + ret = -EINVAL; + } + + if (t_calc->div_high > 0xffff) { + t_calc->div_high = 0xffff; + ret = -EINVAL; + } + + return ret; +} + +static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate) +{ + struct i2c_timings *t = &i2c->t; + struct rk3x_i2c_calced_timings calc; + u64 t_low_ns, t_high_ns; + unsigned long flags; + u32 val; + int ret; + + ret = i2c->soc_data->calc_timings(clk_rate, t, &calc); + WARN_ONCE(ret != 0, "Could not reach SCL freq %u", t->bus_freq_hz); + + clk_enable(i2c->pclk); + + spin_lock_irqsave(&i2c->lock, flags); + val = i2c_readl(i2c, REG_CON); + val &= ~REG_CON_TUNING_MASK; + val |= calc.tuning; + i2c_writel(i2c, val, REG_CON); + i2c_writel(i2c, (calc.div_high << 16) | (calc.div_low & 0xffff), + REG_CLKDIV); + spin_unlock_irqrestore(&i2c->lock, flags); + + clk_disable(i2c->pclk); + + t_low_ns = div_u64(((u64)calc.div_low + 1) * 8 * 1000000000, clk_rate); + t_high_ns = div_u64(((u64)calc.div_high + 1) * 8 * 1000000000, + clk_rate); + dev_dbg(i2c->dev, + "CLK %lukhz, Req %uns, Act low %lluns high %lluns\n", + clk_rate / 1000, + 1000000000 / t->bus_freq_hz, + t_low_ns, t_high_ns); +} + +/** + * rk3x_i2c_clk_notifier_cb - Clock rate change callback + * @nb: Pointer to notifier block + * @event: Notification reason + * @data: Pointer to notification data object + * + * The callback checks whether a valid bus frequency can be generated after the + * change. If so, the change is acknowledged, otherwise the change is aborted. + * New dividers are written to the HW in the pre- or post change notification + * depending on the scaling direction. + * + * Code adapted from i2c-cadence.c. + * + * Return: NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK + * to acknowledge the change, NOTIFY_DONE if the notification is + * considered irrelevant. + */ +static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long + event, void *data) +{ + struct clk_notifier_data *ndata = data; + struct rk3x_i2c *i2c = container_of(nb, struct rk3x_i2c, clk_rate_nb); + struct rk3x_i2c_calced_timings calc; + + switch (event) { + case PRE_RATE_CHANGE: + /* + * Try the calculation (but don't store the result) ahead of + * time to see if we need to block the clock change. Timings + * shouldn't actually take effect until rk3x_i2c_adapt_div(). + */ + if (i2c->soc_data->calc_timings(ndata->new_rate, &i2c->t, + &calc) != 0) + return NOTIFY_STOP; + + /* scale up */ + if (ndata->new_rate > ndata->old_rate) + rk3x_i2c_adapt_div(i2c, ndata->new_rate); + + return NOTIFY_OK; + case POST_RATE_CHANGE: + /* scale down */ + if (ndata->new_rate < ndata->old_rate) + rk3x_i2c_adapt_div(i2c, ndata->new_rate); + return NOTIFY_OK; + case ABORT_RATE_CHANGE: + /* scale up */ + if (ndata->new_rate > ndata->old_rate) + rk3x_i2c_adapt_div(i2c, ndata->old_rate); + return NOTIFY_OK; + default: + return NOTIFY_DONE; + } +} + +/** + * rk3x_i2c_setup - Setup I2C registers for an I2C operation specified by msgs, num. + * @i2c: target controller data + * @msgs: I2C msgs to process + * @num: Number of msgs + * + * Must be called with i2c->lock held. + * + * Return: Number of I2C msgs processed or negative in case of error + */ +static int rk3x_i2c_setup(struct rk3x_i2c *i2c, struct i2c_msg *msgs, int num) +{ + u32 addr = (msgs[0].addr & 0x7f) << 1; + int ret = 0; + + /* + * The I2C adapter can issue a small (len < 4) write packet before + * reading. This speeds up SMBus-style register reads. + * The MRXADDR/MRXRADDR hold the slave address and the slave register + * address in this case. + */ + + if (num >= 2 && msgs[0].len < 4 && + !(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD)) { + u32 reg_addr = 0; + int i; + + dev_dbg(i2c->dev, "Combined write/read from addr 0x%x\n", + addr >> 1); + + /* Fill MRXRADDR with the register address(es) */ + for (i = 0; i < msgs[0].len; ++i) { + reg_addr |= msgs[0].buf[i] << (i * 8); + reg_addr |= REG_MRXADDR_VALID(i); + } + + /* msgs[0] is handled by hw. */ + i2c->msg = &msgs[1]; + + i2c->mode = REG_CON_MOD_REGISTER_TX; + + i2c_writel(i2c, addr | REG_MRXADDR_VALID(0), REG_MRXADDR); + i2c_writel(i2c, reg_addr, REG_MRXRADDR); + + ret = 2; + } else { + /* + * We'll have to do it the boring way and process the msgs + * one-by-one. + */ + + if (msgs[0].flags & I2C_M_RD) { + addr |= 1; /* set read bit */ + + /* + * We have to transmit the slave addr first. Use + * MOD_REGISTER_TX for that purpose. + */ + i2c->mode = REG_CON_MOD_REGISTER_TX; + i2c_writel(i2c, addr | REG_MRXADDR_VALID(0), + REG_MRXADDR); + i2c_writel(i2c, 0, REG_MRXRADDR); + } else { + i2c->mode = REG_CON_MOD_TX; + } + + i2c->msg = &msgs[0]; + + ret = 1; + } + + i2c->addr = msgs[0].addr; + i2c->busy = true; + i2c->state = STATE_START; + i2c->processed = 0; + i2c->error = 0; + + rk3x_i2c_clean_ipd(i2c); + + return ret; +} + +static int rk3x_i2c_wait_xfer_poll(struct rk3x_i2c *i2c) +{ + ktime_t timeout = ktime_add_ms(ktime_get(), WAIT_TIMEOUT); + + while (READ_ONCE(i2c->busy) && + ktime_compare(ktime_get(), timeout) < 0) { + udelay(5); + rk3x_i2c_irq(0, i2c); + } + + return !i2c->busy; +} + +static int rk3x_i2c_xfer_common(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num, bool polling) +{ + struct rk3x_i2c *i2c = (struct rk3x_i2c *)adap->algo_data; + unsigned long timeout, flags; + u32 val; + int ret = 0; + int i; + + spin_lock_irqsave(&i2c->lock, flags); + + clk_enable(i2c->clk); + clk_enable(i2c->pclk); + + i2c->is_last_msg = false; + + /* + * Process msgs. We can handle more than one message at once (see + * rk3x_i2c_setup()). + */ + for (i = 0; i < num; i += ret) { + ret = rk3x_i2c_setup(i2c, msgs + i, num - i); + + if (ret < 0) { + dev_err(i2c->dev, "rk3x_i2c_setup() failed\n"); + break; + } + + if (i + ret >= num) + i2c->is_last_msg = true; + + spin_unlock_irqrestore(&i2c->lock, flags); + + if (!polling) { + rk3x_i2c_start(i2c); + + timeout = wait_event_timeout(i2c->wait, !i2c->busy, + msecs_to_jiffies(WAIT_TIMEOUT)); + } else { + disable_irq(i2c->irq); + rk3x_i2c_start(i2c); + + timeout = rk3x_i2c_wait_xfer_poll(i2c); + + enable_irq(i2c->irq); + } + + spin_lock_irqsave(&i2c->lock, flags); + + if (timeout == 0) { + dev_err(i2c->dev, "timeout, ipd: 0x%02x, state: %d\n", + i2c_readl(i2c, REG_IPD), i2c->state); + + /* Force a STOP condition without interrupt */ + i2c_writel(i2c, 0, REG_IEN); + val = i2c_readl(i2c, REG_CON) & REG_CON_TUNING_MASK; + val |= REG_CON_EN | REG_CON_STOP; + i2c_writel(i2c, val, REG_CON); + + i2c->state = STATE_IDLE; + + ret = -ETIMEDOUT; + break; + } + + if (i2c->error) { + ret = i2c->error; + break; + } + } + + clk_disable(i2c->pclk); + clk_disable(i2c->clk); + + spin_unlock_irqrestore(&i2c->lock, flags); + + return ret < 0 ? ret : num; +} + +static int rk3x_i2c_xfer(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + return rk3x_i2c_xfer_common(adap, msgs, num, false); +} + +static int rk3x_i2c_xfer_polling(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + return rk3x_i2c_xfer_common(adap, msgs, num, true); +} + +static __maybe_unused int rk3x_i2c_resume(struct device *dev) +{ + struct rk3x_i2c *i2c = dev_get_drvdata(dev); + + rk3x_i2c_adapt_div(i2c, clk_get_rate(i2c->clk)); + + return 0; +} + +static u32 rk3x_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING; +} + +static const struct i2c_algorithm rk3x_i2c_algorithm = { + .master_xfer = rk3x_i2c_xfer, + .master_xfer_atomic = rk3x_i2c_xfer_polling, + .functionality = rk3x_i2c_func, +}; + +static const struct rk3x_i2c_soc_data rv1108_soc_data = { + .grf_offset = -1, + .calc_timings = rk3x_i2c_v1_calc_timings, +}; + +static const struct rk3x_i2c_soc_data rv1126_soc_data = { + .grf_offset = 0x118, + .calc_timings = rk3x_i2c_v1_calc_timings, +}; + +static const struct rk3x_i2c_soc_data rk3066_soc_data = { + .grf_offset = 0x154, + .calc_timings = rk3x_i2c_v0_calc_timings, +}; + +static const struct rk3x_i2c_soc_data rk3188_soc_data = { + .grf_offset = 0x0a4, + .calc_timings = rk3x_i2c_v0_calc_timings, +}; + +static const struct rk3x_i2c_soc_data rk3228_soc_data = { + .grf_offset = -1, + .calc_timings = rk3x_i2c_v0_calc_timings, +}; + +static const struct rk3x_i2c_soc_data rk3288_soc_data = { + .grf_offset = -1, + .calc_timings = rk3x_i2c_v0_calc_timings, +}; + +static const struct rk3x_i2c_soc_data rk3399_soc_data = { + .grf_offset = -1, + .calc_timings = rk3x_i2c_v1_calc_timings, +}; + +static const struct of_device_id rk3x_i2c_match[] = { + { + .compatible = "rockchip,rv1108-i2c", + .data = &rv1108_soc_data + }, + { + .compatible = "rockchip,rv1126-i2c", + .data = &rv1126_soc_data + }, + { + .compatible = "rockchip,rk3066-i2c", + .data = &rk3066_soc_data + }, + { + .compatible = "rockchip,rk3188-i2c", + .data = &rk3188_soc_data + }, + { + .compatible = "rockchip,rk3228-i2c", + .data = &rk3228_soc_data + }, + { + .compatible = "rockchip,rk3288-i2c", + .data = &rk3288_soc_data + }, + { + .compatible = "rockchip,rk3399-i2c", + .data = &rk3399_soc_data + }, + {}, +}; +MODULE_DEVICE_TABLE(of, rk3x_i2c_match); + +static int rk3x_i2c_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + const struct of_device_id *match; + struct rk3x_i2c *i2c; + int ret = 0; + int bus_nr; + u32 value; + int irq; + unsigned long clk_rate; + + i2c = devm_kzalloc(&pdev->dev, sizeof(struct rk3x_i2c), GFP_KERNEL); + if (!i2c) + return -ENOMEM; + + match = of_match_node(rk3x_i2c_match, np); + i2c->soc_data = match->data; + + /* use common interface to get I2C timing properties */ + i2c_parse_fw_timings(&pdev->dev, &i2c->t, true); + + strscpy(i2c->adap.name, "rk3x-i2c", sizeof(i2c->adap.name)); + i2c->adap.owner = THIS_MODULE; + i2c->adap.algo = &rk3x_i2c_algorithm; + i2c->adap.retries = 3; + i2c->adap.dev.of_node = np; + i2c->adap.algo_data = i2c; + i2c->adap.dev.parent = &pdev->dev; + + i2c->dev = &pdev->dev; + + spin_lock_init(&i2c->lock); + init_waitqueue_head(&i2c->wait); + + i2c->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(i2c->regs)) + return PTR_ERR(i2c->regs); + + /* Try to set the I2C adapter number from dt */ + bus_nr = of_alias_get_id(np, "i2c"); + + /* + * Switch to new interface if the SoC also offers the old one. + * The control bit is located in the GRF register space. + */ + if (i2c->soc_data->grf_offset >= 0) { + struct regmap *grf; + + grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf"); + if (IS_ERR(grf)) { + dev_err(&pdev->dev, + "rk3x-i2c needs 'rockchip,grf' property\n"); + return PTR_ERR(grf); + } + + if (bus_nr < 0) { + dev_err(&pdev->dev, "rk3x-i2c needs i2cX alias"); + return -EINVAL; + } + + /* 27+i: write mask, 11+i: value */ + value = BIT(27 + bus_nr) | BIT(11 + bus_nr); + + ret = regmap_write(grf, i2c->soc_data->grf_offset, value); + if (ret != 0) { + dev_err(i2c->dev, "Could not write to GRF: %d\n", ret); + return ret; + } + } + + /* IRQ setup */ + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + ret = devm_request_irq(&pdev->dev, irq, rk3x_i2c_irq, + 0, dev_name(&pdev->dev), i2c); + if (ret < 0) { + dev_err(&pdev->dev, "cannot request IRQ\n"); + return ret; + } + + i2c->irq = irq; + + platform_set_drvdata(pdev, i2c); + + if (i2c->soc_data->calc_timings == rk3x_i2c_v0_calc_timings) { + /* Only one clock to use for bus clock and peripheral clock */ + i2c->clk = devm_clk_get(&pdev->dev, NULL); + i2c->pclk = i2c->clk; + } else { + i2c->clk = devm_clk_get(&pdev->dev, "i2c"); + i2c->pclk = devm_clk_get(&pdev->dev, "pclk"); + } + + if (IS_ERR(i2c->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk), + "Can't get bus clk\n"); + + if (IS_ERR(i2c->pclk)) + return dev_err_probe(&pdev->dev, PTR_ERR(i2c->pclk), + "Can't get periph clk\n"); + + ret = clk_prepare(i2c->clk); + if (ret < 0) { + dev_err(&pdev->dev, "Can't prepare bus clk: %d\n", ret); + return ret; + } + ret = clk_prepare(i2c->pclk); + if (ret < 0) { + dev_err(&pdev->dev, "Can't prepare periph clock: %d\n", ret); + goto err_clk; + } + + i2c->clk_rate_nb.notifier_call = rk3x_i2c_clk_notifier_cb; + ret = clk_notifier_register(i2c->clk, &i2c->clk_rate_nb); + if (ret != 0) { + dev_err(&pdev->dev, "Unable to register clock notifier\n"); + goto err_pclk; + } + + ret = clk_enable(i2c->clk); + if (ret < 0) { + dev_err(&pdev->dev, "Can't enable bus clk: %d\n", ret); + goto err_clk_notifier; + } + + clk_rate = clk_get_rate(i2c->clk); + rk3x_i2c_adapt_div(i2c, clk_rate); + clk_disable(i2c->clk); + + ret = i2c_add_adapter(&i2c->adap); + if (ret < 0) + goto err_clk_notifier; + + return 0; + +err_clk_notifier: + clk_notifier_unregister(i2c->clk, &i2c->clk_rate_nb); +err_pclk: + clk_unprepare(i2c->pclk); +err_clk: + clk_unprepare(i2c->clk); + return ret; +} + +static void rk3x_i2c_remove(struct platform_device *pdev) +{ + struct rk3x_i2c *i2c = platform_get_drvdata(pdev); + + i2c_del_adapter(&i2c->adap); + + clk_notifier_unregister(i2c->clk, &i2c->clk_rate_nb); + clk_unprepare(i2c->pclk); + clk_unprepare(i2c->clk); +} + +static SIMPLE_DEV_PM_OPS(rk3x_i2c_pm_ops, NULL, rk3x_i2c_resume); + +static struct platform_driver rk3x_i2c_driver = { + .probe = rk3x_i2c_probe, + .remove_new = rk3x_i2c_remove, + .driver = { + .name = "rk3x-i2c", + .of_match_table = rk3x_i2c_match, + .pm = &rk3x_i2c_pm_ops, + }, +}; + +module_platform_driver(rk3x_i2c_driver); + +MODULE_DESCRIPTION("Rockchip RK3xxx I2C Bus driver"); +MODULE_AUTHOR("Max Schwarz <max.schwarz@online.de>"); +MODULE_LICENSE("GPL v2"); |