diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/i2c/busses/i2c-axxia.c | 626 |
1 files changed, 626 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-axxia.c b/drivers/i2c/busses/i2c-axxia.c new file mode 100644 index 000000000..fb5bac079 --- /dev/null +++ b/drivers/i2c/busses/i2c-axxia.c @@ -0,0 +1,626 @@ +/* + * This driver implements I2C master functionality using the LSI API2C + * controller. + * + * NOTE: The controller has a limitation in that it can only do transfers of + * maximum 255 bytes at a time. If a larger transfer is attempted, error code + * (-EINVAL) is returned. + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + */ +#include <linux/clk.h> +#include <linux/clkdev.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> + +#define SCL_WAIT_TIMEOUT_NS 25000000 +#define I2C_XFER_TIMEOUT (msecs_to_jiffies(250)) +#define I2C_STOP_TIMEOUT (msecs_to_jiffies(100)) +#define FIFO_SIZE 8 + +#define GLOBAL_CONTROL 0x00 +#define GLOBAL_MST_EN BIT(0) +#define GLOBAL_SLV_EN BIT(1) +#define GLOBAL_IBML_EN BIT(2) +#define INTERRUPT_STATUS 0x04 +#define INTERRUPT_ENABLE 0x08 +#define INT_SLV BIT(1) +#define INT_MST BIT(0) +#define WAIT_TIMER_CONTROL 0x0c +#define WT_EN BIT(15) +#define WT_VALUE(_x) ((_x) & 0x7fff) +#define IBML_TIMEOUT 0x10 +#define IBML_LOW_MEXT 0x14 +#define IBML_LOW_SEXT 0x18 +#define TIMER_CLOCK_DIV 0x1c +#define I2C_BUS_MONITOR 0x20 +#define BM_SDAC BIT(3) +#define BM_SCLC BIT(2) +#define BM_SDAS BIT(1) +#define BM_SCLS BIT(0) +#define SOFT_RESET 0x24 +#define MST_COMMAND 0x28 +#define CMD_BUSY (1<<3) +#define CMD_MANUAL (0x00 | CMD_BUSY) +#define CMD_AUTO (0x01 | CMD_BUSY) +#define MST_RX_XFER 0x2c +#define MST_TX_XFER 0x30 +#define MST_ADDR_1 0x34 +#define MST_ADDR_2 0x38 +#define MST_DATA 0x3c +#define MST_TX_FIFO 0x40 +#define MST_RX_FIFO 0x44 +#define MST_INT_ENABLE 0x48 +#define MST_INT_STATUS 0x4c +#define MST_STATUS_RFL (1 << 13) /* RX FIFO serivce */ +#define MST_STATUS_TFL (1 << 12) /* TX FIFO service */ +#define MST_STATUS_SNS (1 << 11) /* Manual mode done */ +#define MST_STATUS_SS (1 << 10) /* Automatic mode done */ +#define MST_STATUS_SCC (1 << 9) /* Stop complete */ +#define MST_STATUS_IP (1 << 8) /* Invalid parameter */ +#define MST_STATUS_TSS (1 << 7) /* Timeout */ +#define MST_STATUS_AL (1 << 6) /* Arbitration lost */ +#define MST_STATUS_ND (1 << 5) /* NAK on data phase */ +#define MST_STATUS_NA (1 << 4) /* NAK on address phase */ +#define MST_STATUS_NAK (MST_STATUS_NA | \ + MST_STATUS_ND) +#define MST_STATUS_ERR (MST_STATUS_NAK | \ + MST_STATUS_AL | \ + MST_STATUS_IP) +#define MST_TX_BYTES_XFRD 0x50 +#define MST_RX_BYTES_XFRD 0x54 +#define SCL_HIGH_PERIOD 0x80 +#define SCL_LOW_PERIOD 0x84 +#define SPIKE_FLTR_LEN 0x88 +#define SDA_SETUP_TIME 0x8c +#define SDA_HOLD_TIME 0x90 + +/** + * axxia_i2c_dev - I2C device context + * @base: pointer to register struct + * @msg: pointer to current message + * @msg_xfrd: number of bytes transferred in msg + * @msg_err: error code for completed message + * @msg_complete: xfer completion object + * @dev: device reference + * @adapter: core i2c abstraction + * @i2c_clk: clock reference for i2c input clock + * @bus_clk_rate: current i2c bus clock rate + */ +struct axxia_i2c_dev { + void __iomem *base; + struct i2c_msg *msg; + size_t msg_xfrd; + int msg_err; + struct completion msg_complete; + struct device *dev; + struct i2c_adapter adapter; + struct clk *i2c_clk; + u32 bus_clk_rate; +}; + +static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask) +{ + u32 int_en; + + int_en = readl(idev->base + MST_INT_ENABLE); + writel(int_en & ~mask, idev->base + MST_INT_ENABLE); +} + +static void i2c_int_enable(struct axxia_i2c_dev *idev, u32 mask) +{ + u32 int_en; + + int_en = readl(idev->base + MST_INT_ENABLE); + writel(int_en | mask, idev->base + MST_INT_ENABLE); +} + +/** + * ns_to_clk - Convert time (ns) to clock cycles for the given clock frequency. + */ +static u32 ns_to_clk(u64 ns, u32 clk_mhz) +{ + return div_u64(ns * clk_mhz, 1000); +} + +static int axxia_i2c_init(struct axxia_i2c_dev *idev) +{ + u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate; + u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000; + u32 t_setup; + u32 t_high, t_low; + u32 tmo_clk; + u32 prescale; + unsigned long timeout; + + dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n", + idev->bus_clk_rate, clk_mhz, divisor); + + /* Reset controller */ + writel(0x01, idev->base + SOFT_RESET); + timeout = jiffies + msecs_to_jiffies(100); + while (readl(idev->base + SOFT_RESET) & 1) { + if (time_after(jiffies, timeout)) { + dev_warn(idev->dev, "Soft reset failed\n"); + break; + } + } + + /* Enable Master Mode */ + writel(0x1, idev->base + GLOBAL_CONTROL); + + if (idev->bus_clk_rate <= 100000) { + /* Standard mode SCL 50/50, tSU:DAT = 250 ns */ + t_high = divisor * 1 / 2; + t_low = divisor * 1 / 2; + t_setup = ns_to_clk(250, clk_mhz); + } else { + /* Fast mode SCL 33/66, tSU:DAT = 100 ns */ + t_high = divisor * 1 / 3; + t_low = divisor * 2 / 3; + t_setup = ns_to_clk(100, clk_mhz); + } + + /* SCL High Time */ + writel(t_high, idev->base + SCL_HIGH_PERIOD); + /* SCL Low Time */ + writel(t_low, idev->base + SCL_LOW_PERIOD); + /* SDA Setup Time */ + writel(t_setup, idev->base + SDA_SETUP_TIME); + /* SDA Hold Time, 300ns */ + writel(ns_to_clk(300, clk_mhz), idev->base + SDA_HOLD_TIME); + /* Filter <50ns spikes */ + writel(ns_to_clk(50, clk_mhz), idev->base + SPIKE_FLTR_LEN); + + /* Configure Time-Out Registers */ + tmo_clk = ns_to_clk(SCL_WAIT_TIMEOUT_NS, clk_mhz); + + /* Find prescaler value that makes tmo_clk fit in 15-bits counter. */ + for (prescale = 0; prescale < 15; ++prescale) { + if (tmo_clk <= 0x7fff) + break; + tmo_clk >>= 1; + } + if (tmo_clk > 0x7fff) + tmo_clk = 0x7fff; + + /* Prescale divider (log2) */ + writel(prescale, idev->base + TIMER_CLOCK_DIV); + /* Timeout in divided clocks */ + writel(WT_EN | WT_VALUE(tmo_clk), idev->base + WAIT_TIMER_CONTROL); + + /* Mask all master interrupt bits */ + i2c_int_disable(idev, ~0); + + /* Interrupt enable */ + writel(0x01, idev->base + INTERRUPT_ENABLE); + + return 0; +} + +static int i2c_m_rd(const struct i2c_msg *msg) +{ + return (msg->flags & I2C_M_RD) != 0; +} + +static int i2c_m_ten(const struct i2c_msg *msg) +{ + return (msg->flags & I2C_M_TEN) != 0; +} + +static int i2c_m_recv_len(const struct i2c_msg *msg) +{ + return (msg->flags & I2C_M_RECV_LEN) != 0; +} + +/** + * axxia_i2c_empty_rx_fifo - Fetch data from RX FIFO and update SMBus block + * transfer length if this is the first byte of such a transfer. + */ +static int axxia_i2c_empty_rx_fifo(struct axxia_i2c_dev *idev) +{ + struct i2c_msg *msg = idev->msg; + size_t rx_fifo_avail = readl(idev->base + MST_RX_FIFO); + int bytes_to_transfer = min(rx_fifo_avail, msg->len - idev->msg_xfrd); + + while (bytes_to_transfer-- > 0) { + int c = readl(idev->base + MST_DATA); + + if (idev->msg_xfrd == 0 && i2c_m_recv_len(msg)) { + /* + * Check length byte for SMBus block read + */ + if (c <= 0 || c > I2C_SMBUS_BLOCK_MAX) { + idev->msg_err = -EPROTO; + i2c_int_disable(idev, ~MST_STATUS_TSS); + complete(&idev->msg_complete); + break; + } + msg->len = 1 + c; + writel(msg->len, idev->base + MST_RX_XFER); + } + msg->buf[idev->msg_xfrd++] = c; + } + + return 0; +} + +/** + * axxia_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer. + * @return: Number of bytes left to transfer. + */ +static int axxia_i2c_fill_tx_fifo(struct axxia_i2c_dev *idev) +{ + struct i2c_msg *msg = idev->msg; + size_t tx_fifo_avail = FIFO_SIZE - readl(idev->base + MST_TX_FIFO); + int bytes_to_transfer = min(tx_fifo_avail, msg->len - idev->msg_xfrd); + int ret = msg->len - idev->msg_xfrd - bytes_to_transfer; + + while (bytes_to_transfer-- > 0) + writel(msg->buf[idev->msg_xfrd++], idev->base + MST_DATA); + + return ret; +} + +static irqreturn_t axxia_i2c_isr(int irq, void *_dev) +{ + struct axxia_i2c_dev *idev = _dev; + u32 status; + + if (!(readl(idev->base + INTERRUPT_STATUS) & INT_MST)) + return IRQ_NONE; + + /* Read interrupt status bits */ + status = readl(idev->base + MST_INT_STATUS); + + if (!idev->msg) { + dev_warn(idev->dev, "unexpected interrupt\n"); + goto out; + } + + /* RX FIFO needs service? */ + if (i2c_m_rd(idev->msg) && (status & MST_STATUS_RFL)) + axxia_i2c_empty_rx_fifo(idev); + + /* TX FIFO needs service? */ + if (!i2c_m_rd(idev->msg) && (status & MST_STATUS_TFL)) { + if (axxia_i2c_fill_tx_fifo(idev) == 0) + i2c_int_disable(idev, MST_STATUS_TFL); + } + + if (unlikely(status & MST_STATUS_ERR)) { + /* Transfer error */ + i2c_int_disable(idev, ~0); + if (status & MST_STATUS_AL) + idev->msg_err = -EAGAIN; + else if (status & MST_STATUS_NAK) + idev->msg_err = -ENXIO; + else + idev->msg_err = -EIO; + dev_dbg(idev->dev, "error %#x, addr=%#x rx=%u/%u tx=%u/%u\n", + status, + idev->msg->addr, + readl(idev->base + MST_RX_BYTES_XFRD), + readl(idev->base + MST_RX_XFER), + readl(idev->base + MST_TX_BYTES_XFRD), + readl(idev->base + MST_TX_XFER)); + complete(&idev->msg_complete); + } else if (status & MST_STATUS_SCC) { + /* Stop completed */ + i2c_int_disable(idev, ~MST_STATUS_TSS); + complete(&idev->msg_complete); + } else if (status & MST_STATUS_SNS) { + /* Transfer done */ + i2c_int_disable(idev, ~MST_STATUS_TSS); + if (i2c_m_rd(idev->msg) && idev->msg_xfrd < idev->msg->len) + axxia_i2c_empty_rx_fifo(idev); + complete(&idev->msg_complete); + } else if (status & MST_STATUS_TSS) { + /* Transfer timeout */ + idev->msg_err = -ETIMEDOUT; + i2c_int_disable(idev, ~MST_STATUS_TSS); + complete(&idev->msg_complete); + } + +out: + /* Clear interrupt */ + writel(INT_MST, idev->base + INTERRUPT_STATUS); + + return IRQ_HANDLED; +} + +static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg) +{ + u32 int_mask = MST_STATUS_ERR | MST_STATUS_SNS; + u32 rx_xfer, tx_xfer; + u32 addr_1, addr_2; + unsigned long time_left; + unsigned int wt_value; + + idev->msg = msg; + idev->msg_xfrd = 0; + reinit_completion(&idev->msg_complete); + + if (i2c_m_ten(msg)) { + /* 10-bit address + * addr_1: 5'b11110 | addr[9:8] | (R/nW) + * addr_2: addr[7:0] + */ + addr_1 = 0xF0 | ((msg->addr >> 7) & 0x06); + if (i2c_m_rd(msg)) + addr_1 |= 1; /* Set the R/nW bit of the address */ + addr_2 = msg->addr & 0xFF; + } else { + /* 7-bit address + * addr_1: addr[6:0] | (R/nW) + * addr_2: dont care + */ + addr_1 = i2c_8bit_addr_from_msg(msg); + addr_2 = 0; + } + + if (i2c_m_rd(msg)) { + /* I2C read transfer */ + rx_xfer = i2c_m_recv_len(msg) ? I2C_SMBUS_BLOCK_MAX : msg->len; + tx_xfer = 0; + } else { + /* I2C write transfer */ + rx_xfer = 0; + tx_xfer = msg->len; + } + + writel(rx_xfer, idev->base + MST_RX_XFER); + writel(tx_xfer, idev->base + MST_TX_XFER); + writel(addr_1, idev->base + MST_ADDR_1); + writel(addr_2, idev->base + MST_ADDR_2); + + if (i2c_m_rd(msg)) + int_mask |= MST_STATUS_RFL; + else if (axxia_i2c_fill_tx_fifo(idev) != 0) + int_mask |= MST_STATUS_TFL; + + wt_value = WT_VALUE(readl(idev->base + WAIT_TIMER_CONTROL)); + /* Disable wait timer temporarly */ + writel(wt_value, idev->base + WAIT_TIMER_CONTROL); + /* Check if timeout error happened */ + if (idev->msg_err) + goto out; + + /* Start manual mode */ + writel(CMD_MANUAL, idev->base + MST_COMMAND); + + writel(WT_EN | wt_value, idev->base + WAIT_TIMER_CONTROL); + + i2c_int_enable(idev, int_mask); + + time_left = wait_for_completion_timeout(&idev->msg_complete, + I2C_XFER_TIMEOUT); + + i2c_int_disable(idev, int_mask); + + if (readl(idev->base + MST_COMMAND) & CMD_BUSY) + dev_warn(idev->dev, "busy after xfer\n"); + + if (time_left == 0) { + idev->msg_err = -ETIMEDOUT; + i2c_recover_bus(&idev->adapter); + axxia_i2c_init(idev); + } + +out: + if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO && + idev->msg_err != -ETIMEDOUT) + axxia_i2c_init(idev); + + return idev->msg_err; +} + +static int axxia_i2c_stop(struct axxia_i2c_dev *idev) +{ + u32 int_mask = MST_STATUS_ERR | MST_STATUS_SCC | MST_STATUS_TSS; + unsigned long time_left; + + reinit_completion(&idev->msg_complete); + + /* Issue stop */ + writel(0xb, idev->base + MST_COMMAND); + i2c_int_enable(idev, int_mask); + time_left = wait_for_completion_timeout(&idev->msg_complete, + I2C_STOP_TIMEOUT); + i2c_int_disable(idev, int_mask); + if (time_left == 0) + return -ETIMEDOUT; + + if (readl(idev->base + MST_COMMAND) & CMD_BUSY) + dev_warn(idev->dev, "busy after stop\n"); + + return 0; +} + +static int +axxia_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) +{ + struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); + int i; + int ret = 0; + + idev->msg_err = 0; + i2c_int_enable(idev, MST_STATUS_TSS); + + for (i = 0; ret == 0 && i < num; ++i) + ret = axxia_i2c_xfer_msg(idev, &msgs[i]); + + axxia_i2c_stop(idev); + + return ret ? : i; +} + +static int axxia_i2c_get_scl(struct i2c_adapter *adap) +{ + struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); + + return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SCLS); +} + +static void axxia_i2c_set_scl(struct i2c_adapter *adap, int val) +{ + struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); + u32 tmp; + + /* Preserve SDA Control */ + tmp = readl(idev->base + I2C_BUS_MONITOR) & BM_SDAC; + if (!val) + tmp |= BM_SCLC; + writel(tmp, idev->base + I2C_BUS_MONITOR); +} + +static int axxia_i2c_get_sda(struct i2c_adapter *adap) +{ + struct axxia_i2c_dev *idev = i2c_get_adapdata(adap); + + return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SDAS); +} + +static struct i2c_bus_recovery_info axxia_i2c_recovery_info = { + .recover_bus = i2c_generic_scl_recovery, + .get_scl = axxia_i2c_get_scl, + .set_scl = axxia_i2c_set_scl, + .get_sda = axxia_i2c_get_sda, +}; + +static u32 axxia_i2c_func(struct i2c_adapter *adap) +{ + u32 caps = (I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | + I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA); + return caps; +} + +static const struct i2c_algorithm axxia_i2c_algo = { + .master_xfer = axxia_i2c_xfer, + .functionality = axxia_i2c_func, +}; + +static const struct i2c_adapter_quirks axxia_i2c_quirks = { + .max_read_len = 255, + .max_write_len = 255, +}; + +static int axxia_i2c_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct axxia_i2c_dev *idev = NULL; + struct resource *res; + void __iomem *base; + int irq; + int ret = 0; + + idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL); + if (!idev) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(base)) + return PTR_ERR(base); + + irq = platform_get_irq(pdev, 0); + if (irq < 0) { + dev_err(&pdev->dev, "missing interrupt resource\n"); + return irq; + } + + idev->i2c_clk = devm_clk_get(&pdev->dev, "i2c"); + if (IS_ERR(idev->i2c_clk)) { + dev_err(&pdev->dev, "missing clock\n"); + return PTR_ERR(idev->i2c_clk); + } + + idev->base = base; + idev->dev = &pdev->dev; + init_completion(&idev->msg_complete); + + of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate); + if (idev->bus_clk_rate == 0) + idev->bus_clk_rate = 100000; /* default clock rate */ + + ret = clk_prepare_enable(idev->i2c_clk); + if (ret) { + dev_err(&pdev->dev, "failed to enable clock\n"); + return ret; + } + + ret = axxia_i2c_init(idev); + if (ret) { + dev_err(&pdev->dev, "failed to initialize\n"); + goto error_disable_clk; + } + + ret = devm_request_irq(&pdev->dev, irq, axxia_i2c_isr, 0, + pdev->name, idev); + if (ret) { + dev_err(&pdev->dev, "failed to claim IRQ%d\n", irq); + goto error_disable_clk; + } + + i2c_set_adapdata(&idev->adapter, idev); + strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name)); + idev->adapter.owner = THIS_MODULE; + idev->adapter.algo = &axxia_i2c_algo; + idev->adapter.bus_recovery_info = &axxia_i2c_recovery_info; + idev->adapter.quirks = &axxia_i2c_quirks; + idev->adapter.dev.parent = &pdev->dev; + idev->adapter.dev.of_node = pdev->dev.of_node; + + platform_set_drvdata(pdev, idev); + + ret = i2c_add_adapter(&idev->adapter); + if (ret) + goto error_disable_clk; + + return 0; + +error_disable_clk: + clk_disable_unprepare(idev->i2c_clk); + return ret; +} + +static int axxia_i2c_remove(struct platform_device *pdev) +{ + struct axxia_i2c_dev *idev = platform_get_drvdata(pdev); + + clk_disable_unprepare(idev->i2c_clk); + i2c_del_adapter(&idev->adapter); + + return 0; +} + +/* Match table for of_platform binding */ +static const struct of_device_id axxia_i2c_of_match[] = { + { .compatible = "lsi,api2c", }, + {}, +}; + +MODULE_DEVICE_TABLE(of, axxia_i2c_of_match); + +static struct platform_driver axxia_i2c_driver = { + .probe = axxia_i2c_probe, + .remove = axxia_i2c_remove, + .driver = { + .name = "axxia-i2c", + .of_match_table = axxia_i2c_of_match, + }, +}; + +module_platform_driver(axxia_i2c_driver); + +MODULE_DESCRIPTION("Axxia I2C Bus driver"); +MODULE_AUTHOR("Anders Berg <anders.berg@lsi.com>"); +MODULE_LICENSE("GPL v2"); |