diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-stm32f4.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-stm32f4.c | 894 |
1 files changed, 894 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-stm32f4.c b/drivers/i2c/busses/i2c-stm32f4.c new file mode 100644 index 000000000..ba600d77a --- /dev/null +++ b/drivers/i2c/busses/i2c-stm32f4.c @@ -0,0 +1,894 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Driver for STMicroelectronics STM32 I2C controller + * + * This I2C controller is described in the STM32F429/439 Soc reference manual. + * Please see below a link to the documentation: + * http://www.st.com/resource/en/reference_manual/DM00031020.pdf + * + * Copyright (C) M'boumba Cedric Madianga 2016 + * Copyright (C) STMicroelectronics 2017 + * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com> + * + * This driver is based on i2c-st.c + * + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/module.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/reset.h> + +#include "i2c-stm32.h" + +/* STM32F4 I2C offset registers */ +#define STM32F4_I2C_CR1 0x00 +#define STM32F4_I2C_CR2 0x04 +#define STM32F4_I2C_DR 0x10 +#define STM32F4_I2C_SR1 0x14 +#define STM32F4_I2C_SR2 0x18 +#define STM32F4_I2C_CCR 0x1C +#define STM32F4_I2C_TRISE 0x20 +#define STM32F4_I2C_FLTR 0x24 + +/* STM32F4 I2C control 1*/ +#define STM32F4_I2C_CR1_POS BIT(11) +#define STM32F4_I2C_CR1_ACK BIT(10) +#define STM32F4_I2C_CR1_STOP BIT(9) +#define STM32F4_I2C_CR1_START BIT(8) +#define STM32F4_I2C_CR1_PE BIT(0) + +/* STM32F4 I2C control 2 */ +#define STM32F4_I2C_CR2_FREQ_MASK GENMASK(5, 0) +#define STM32F4_I2C_CR2_FREQ(n) ((n) & STM32F4_I2C_CR2_FREQ_MASK) +#define STM32F4_I2C_CR2_ITBUFEN BIT(10) +#define STM32F4_I2C_CR2_ITEVTEN BIT(9) +#define STM32F4_I2C_CR2_ITERREN BIT(8) +#define STM32F4_I2C_CR2_IRQ_MASK (STM32F4_I2C_CR2_ITBUFEN | \ + STM32F4_I2C_CR2_ITEVTEN | \ + STM32F4_I2C_CR2_ITERREN) + +/* STM32F4 I2C Status 1 */ +#define STM32F4_I2C_SR1_AF BIT(10) +#define STM32F4_I2C_SR1_ARLO BIT(9) +#define STM32F4_I2C_SR1_BERR BIT(8) +#define STM32F4_I2C_SR1_TXE BIT(7) +#define STM32F4_I2C_SR1_RXNE BIT(6) +#define STM32F4_I2C_SR1_BTF BIT(2) +#define STM32F4_I2C_SR1_ADDR BIT(1) +#define STM32F4_I2C_SR1_SB BIT(0) +#define STM32F4_I2C_SR1_ITEVTEN_MASK (STM32F4_I2C_SR1_BTF | \ + STM32F4_I2C_SR1_ADDR | \ + STM32F4_I2C_SR1_SB) +#define STM32F4_I2C_SR1_ITBUFEN_MASK (STM32F4_I2C_SR1_TXE | \ + STM32F4_I2C_SR1_RXNE) +#define STM32F4_I2C_SR1_ITERREN_MASK (STM32F4_I2C_SR1_AF | \ + STM32F4_I2C_SR1_ARLO | \ + STM32F4_I2C_SR1_BERR) + +/* STM32F4 I2C Status 2 */ +#define STM32F4_I2C_SR2_BUSY BIT(1) + +/* STM32F4 I2C Control Clock */ +#define STM32F4_I2C_CCR_CCR_MASK GENMASK(11, 0) +#define STM32F4_I2C_CCR_CCR(n) ((n) & STM32F4_I2C_CCR_CCR_MASK) +#define STM32F4_I2C_CCR_FS BIT(15) +#define STM32F4_I2C_CCR_DUTY BIT(14) + +/* STM32F4 I2C Trise */ +#define STM32F4_I2C_TRISE_VALUE_MASK GENMASK(5, 0) +#define STM32F4_I2C_TRISE_VALUE(n) ((n) & STM32F4_I2C_TRISE_VALUE_MASK) + +#define STM32F4_I2C_MIN_STANDARD_FREQ 2U +#define STM32F4_I2C_MIN_FAST_FREQ 6U +#define STM32F4_I2C_MAX_FREQ 46U +#define HZ_TO_MHZ 1000000 + +/** + * struct stm32f4_i2c_msg - client specific data + * @addr: 8-bit slave addr, including r/w bit + * @count: number of bytes to be transferred + * @buf: data buffer + * @result: result of the transfer + * @stop: last I2C msg to be sent, i.e. STOP to be generated + */ +struct stm32f4_i2c_msg { + u8 addr; + u32 count; + u8 *buf; + int result; + bool stop; +}; + +/** + * struct stm32f4_i2c_dev - private data of the controller + * @adap: I2C adapter for this controller + * @dev: device for this controller + * @base: virtual memory area + * @complete: completion of I2C message + * @clk: hw i2c clock + * @speed: I2C clock frequency of the controller. Standard or Fast are supported + * @parent_rate: I2C clock parent rate in MHz + * @msg: I2C transfer information + */ +struct stm32f4_i2c_dev { + struct i2c_adapter adap; + struct device *dev; + void __iomem *base; + struct completion complete; + struct clk *clk; + int speed; + int parent_rate; + struct stm32f4_i2c_msg msg; +}; + +static inline void stm32f4_i2c_set_bits(void __iomem *reg, u32 mask) +{ + writel_relaxed(readl_relaxed(reg) | mask, reg); +} + +static inline void stm32f4_i2c_clr_bits(void __iomem *reg, u32 mask) +{ + writel_relaxed(readl_relaxed(reg) & ~mask, reg); +} + +static void stm32f4_i2c_disable_irq(struct stm32f4_i2c_dev *i2c_dev) +{ + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2; + + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_IRQ_MASK); +} + +static int stm32f4_i2c_set_periph_clk_freq(struct stm32f4_i2c_dev *i2c_dev) +{ + u32 freq; + u32 cr2 = 0; + + i2c_dev->parent_rate = clk_get_rate(i2c_dev->clk); + freq = DIV_ROUND_UP(i2c_dev->parent_rate, HZ_TO_MHZ); + + if (i2c_dev->speed == STM32_I2C_SPEED_STANDARD) { + /* + * To reach 100 kHz, the parent clk frequency should be between + * a minimum value of 2 MHz and a maximum value of 46 MHz due + * to hardware limitation + */ + if (freq < STM32F4_I2C_MIN_STANDARD_FREQ || + freq > STM32F4_I2C_MAX_FREQ) { + dev_err(i2c_dev->dev, + "bad parent clk freq for standard mode\n"); + return -EINVAL; + } + } else { + /* + * To be as close as possible to 400 kHz, the parent clk + * frequency should be between a minimum value of 6 MHz and a + * maximum value of 46 MHz due to hardware limitation + */ + if (freq < STM32F4_I2C_MIN_FAST_FREQ || + freq > STM32F4_I2C_MAX_FREQ) { + dev_err(i2c_dev->dev, + "bad parent clk freq for fast mode\n"); + return -EINVAL; + } + } + + cr2 |= STM32F4_I2C_CR2_FREQ(freq); + writel_relaxed(cr2, i2c_dev->base + STM32F4_I2C_CR2); + + return 0; +} + +static void stm32f4_i2c_set_rise_time(struct stm32f4_i2c_dev *i2c_dev) +{ + u32 freq = DIV_ROUND_UP(i2c_dev->parent_rate, HZ_TO_MHZ); + u32 trise; + + /* + * These bits must be programmed with the maximum SCL rise time given in + * the I2C bus specification, incremented by 1. + * + * In standard mode, the maximum allowed SCL rise time is 1000 ns. + * If, in the I2C_CR2 register, the value of FREQ[5:0] bits is equal to + * 0x08 so period = 125 ns therefore the TRISE[5:0] bits must be + * programmed with 0x9. (1000 ns / 125 ns + 1) + * So, for I2C standard mode TRISE = FREQ[5:0] + 1 + * + * In fast mode, the maximum allowed SCL rise time is 300 ns. + * If, in the I2C_CR2 register, the value of FREQ[5:0] bits is equal to + * 0x08 so period = 125 ns therefore the TRISE[5:0] bits must be + * programmed with 0x3. (300 ns / 125 ns + 1) + * So, for I2C fast mode TRISE = FREQ[5:0] * 300 / 1000 + 1 + * + * Function stm32f4_i2c_set_periph_clk_freq made sure that parent rate + * is not higher than 46 MHz . As a result trise is at most 4 bits wide + * and so fits into the TRISE bits [5:0]. + */ + if (i2c_dev->speed == STM32_I2C_SPEED_STANDARD) + trise = freq + 1; + else + trise = freq * 3 / 10 + 1; + + writel_relaxed(STM32F4_I2C_TRISE_VALUE(trise), + i2c_dev->base + STM32F4_I2C_TRISE); +} + +static void stm32f4_i2c_set_speed_mode(struct stm32f4_i2c_dev *i2c_dev) +{ + u32 val; + u32 ccr = 0; + + if (i2c_dev->speed == STM32_I2C_SPEED_STANDARD) { + /* + * In standard mode: + * t_scl_high = t_scl_low = CCR * I2C parent clk period + * So to reach 100 kHz, we have: + * CCR = I2C parent rate / 100 kHz >> 1 + * + * For example with parent rate = 2 MHz: + * CCR = 2000000 / (100000 << 1) = 10 + * t_scl_high = t_scl_low = 10 * (1 / 2000000) = 5000 ns + * t_scl_high + t_scl_low = 10000 ns so 100 kHz is reached + * + * Function stm32f4_i2c_set_periph_clk_freq made sure that + * parent rate is not higher than 46 MHz . As a result val + * is at most 8 bits wide and so fits into the CCR bits [11:0]. + */ + val = i2c_dev->parent_rate / (100000 << 1); + } else { + /* + * In fast mode, we compute CCR with duty = 0 as with low + * frequencies we are not able to reach 400 kHz. + * In that case: + * t_scl_high = CCR * I2C parent clk period + * t_scl_low = 2 * CCR * I2C parent clk period + * So, CCR = I2C parent rate / (400 kHz * 3) + * + * For example with parent rate = 6 MHz: + * CCR = 6000000 / (400000 * 3) = 5 + * t_scl_high = 5 * (1 / 6000000) = 833 ns > 600 ns + * t_scl_low = 2 * 5 * (1 / 6000000) = 1667 ns > 1300 ns + * t_scl_high + t_scl_low = 2500 ns so 400 kHz is reached + * + * Function stm32f4_i2c_set_periph_clk_freq made sure that + * parent rate is not higher than 46 MHz . As a result val + * is at most 6 bits wide and so fits into the CCR bits [11:0]. + */ + val = DIV_ROUND_UP(i2c_dev->parent_rate, 400000 * 3); + + /* Select Fast mode */ + ccr |= STM32F4_I2C_CCR_FS; + } + + ccr |= STM32F4_I2C_CCR_CCR(val); + writel_relaxed(ccr, i2c_dev->base + STM32F4_I2C_CCR); +} + +/** + * stm32f4_i2c_hw_config() - Prepare I2C block + * @i2c_dev: Controller's private data + */ +static int stm32f4_i2c_hw_config(struct stm32f4_i2c_dev *i2c_dev) +{ + int ret; + + ret = stm32f4_i2c_set_periph_clk_freq(i2c_dev); + if (ret) + return ret; + + stm32f4_i2c_set_rise_time(i2c_dev); + + stm32f4_i2c_set_speed_mode(i2c_dev); + + /* Enable I2C */ + writel_relaxed(STM32F4_I2C_CR1_PE, i2c_dev->base + STM32F4_I2C_CR1); + + return 0; +} + +static int stm32f4_i2c_wait_free_bus(struct stm32f4_i2c_dev *i2c_dev) +{ + u32 status; + int ret; + + ret = readl_relaxed_poll_timeout(i2c_dev->base + STM32F4_I2C_SR2, + status, + !(status & STM32F4_I2C_SR2_BUSY), + 10, 1000); + if (ret) { + dev_dbg(i2c_dev->dev, "bus not free\n"); + ret = -EBUSY; + } + + return ret; +} + +/** + * stm32f4_i2c_write_ byte() - Write a byte in the data register + * @i2c_dev: Controller's private data + * @byte: Data to write in the register + */ +static void stm32f4_i2c_write_byte(struct stm32f4_i2c_dev *i2c_dev, u8 byte) +{ + writel_relaxed(byte, i2c_dev->base + STM32F4_I2C_DR); +} + +/** + * stm32f4_i2c_write_msg() - Fill the data register in write mode + * @i2c_dev: Controller's private data + * + * This function fills the data register with I2C transfer buffer + */ +static void stm32f4_i2c_write_msg(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + + stm32f4_i2c_write_byte(i2c_dev, *msg->buf++); + msg->count--; +} + +static void stm32f4_i2c_read_msg(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + u32 rbuf; + + rbuf = readl_relaxed(i2c_dev->base + STM32F4_I2C_DR); + *msg->buf++ = rbuf; + msg->count--; +} + +static void stm32f4_i2c_terminate_xfer(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + void __iomem *reg; + + stm32f4_i2c_disable_irq(i2c_dev); + + reg = i2c_dev->base + STM32F4_I2C_CR1; + if (msg->stop) + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); + else + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START); + + complete(&i2c_dev->complete); +} + +/** + * stm32f4_i2c_handle_write() - Handle FIFO empty interrupt in case of write + * @i2c_dev: Controller's private data + */ +static void stm32f4_i2c_handle_write(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2; + + if (msg->count) { + stm32f4_i2c_write_msg(i2c_dev); + if (!msg->count) { + /* + * Disable buffer interrupts for RX not empty and TX + * empty events + */ + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_ITBUFEN); + } + } else { + stm32f4_i2c_terminate_xfer(i2c_dev); + } +} + +/** + * stm32f4_i2c_handle_read() - Handle FIFO empty interrupt in case of read + * @i2c_dev: Controller's private data + * + * This function is called when a new data is received in data register + */ +static void stm32f4_i2c_handle_read(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2; + + switch (msg->count) { + case 1: + stm32f4_i2c_disable_irq(i2c_dev); + stm32f4_i2c_read_msg(i2c_dev); + complete(&i2c_dev->complete); + break; + /* + * For 2-byte reception, 3-byte reception and for Data N-2, N-1 and N + * for N-byte reception with N > 3, we do not have to read the data + * register when RX not empty event occurs as we have to wait for byte + * transferred finished event before reading data. + * So, here we just disable buffer interrupt in order to avoid another + * system preemption due to RX not empty event. + */ + case 2: + case 3: + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_ITBUFEN); + break; + /* + * For N byte reception with N > 3 we directly read data register + * until N-2 data. + */ + default: + stm32f4_i2c_read_msg(i2c_dev); + } +} + +/** + * stm32f4_i2c_handle_rx_done() - Handle byte transfer finished interrupt + * in case of read + * @i2c_dev: Controller's private data + * + * This function is called when a new data is received in the shift register + * but data register has not been read yet. + */ +static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + void __iomem *reg; + u32 mask; + int i; + + switch (msg->count) { + case 2: + /* + * In order to correctly send the Stop or Repeated Start + * condition on the I2C bus, the STOP/START bit has to be set + * before reading the last two bytes (data N-1 and N). + * After that, we could read the last two bytes, disable + * remaining interrupts and notify the end of xfer to the + * client + */ + reg = i2c_dev->base + STM32F4_I2C_CR1; + if (msg->stop) + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); + else + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START); + + for (i = 2; i > 0; i--) + stm32f4_i2c_read_msg(i2c_dev); + + reg = i2c_dev->base + STM32F4_I2C_CR2; + mask = STM32F4_I2C_CR2_ITEVTEN | STM32F4_I2C_CR2_ITERREN; + stm32f4_i2c_clr_bits(reg, mask); + + complete(&i2c_dev->complete); + break; + case 3: + /* + * In order to correctly generate the NACK pulse after the last + * received data byte, we have to enable NACK before reading N-2 + * data + */ + reg = i2c_dev->base + STM32F4_I2C_CR1; + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK); + stm32f4_i2c_read_msg(i2c_dev); + break; + default: + stm32f4_i2c_read_msg(i2c_dev); + } +} + +/** + * stm32f4_i2c_handle_rx_addr() - Handle address matched interrupt in case of + * master receiver + * @i2c_dev: Controller's private data + */ +static void stm32f4_i2c_handle_rx_addr(struct stm32f4_i2c_dev *i2c_dev) +{ + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + u32 cr1; + + switch (msg->count) { + case 0: + stm32f4_i2c_terminate_xfer(i2c_dev); + + /* Clear ADDR flag */ + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); + break; + case 1: + /* + * Single byte reception: + * Enable NACK and reset POS (Acknowledge position). + * Then, clear ADDR flag and set STOP or RepSTART. + * In that way, the NACK and STOP or RepStart pulses will be + * sent as soon as the byte will be received in shift register + */ + cr1 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR1); + cr1 &= ~(STM32F4_I2C_CR1_ACK | STM32F4_I2C_CR1_POS); + writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); + + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); + + if (msg->stop) + cr1 |= STM32F4_I2C_CR1_STOP; + else + cr1 |= STM32F4_I2C_CR1_START; + writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); + break; + case 2: + /* + * 2-byte reception: + * Enable NACK, set POS (NACK position) and clear ADDR flag. + * In that way, NACK will be sent for the next byte which will + * be received in the shift register instead of the current + * one. + */ + cr1 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR1); + cr1 &= ~STM32F4_I2C_CR1_ACK; + cr1 |= STM32F4_I2C_CR1_POS; + writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); + + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); + break; + + default: + /* + * N-byte reception: + * Enable ACK, reset POS (ACK postion) and clear ADDR flag. + * In that way, ACK will be sent as soon as the current byte + * will be received in the shift register + */ + cr1 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR1); + cr1 |= STM32F4_I2C_CR1_ACK; + cr1 &= ~STM32F4_I2C_CR1_POS; + writel_relaxed(cr1, i2c_dev->base + STM32F4_I2C_CR1); + + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); + break; + } +} + +/** + * stm32f4_i2c_isr_event() - Interrupt routine for I2C bus event + * @irq: interrupt number + * @data: Controller's private data + */ +static irqreturn_t stm32f4_i2c_isr_event(int irq, void *data) +{ + struct stm32f4_i2c_dev *i2c_dev = data; + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + u32 possible_status = STM32F4_I2C_SR1_ITEVTEN_MASK; + u32 status, ien, event, cr2; + + cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2); + ien = cr2 & STM32F4_I2C_CR2_IRQ_MASK; + + /* Update possible_status if buffer interrupt is enabled */ + if (ien & STM32F4_I2C_CR2_ITBUFEN) + possible_status |= STM32F4_I2C_SR1_ITBUFEN_MASK; + + status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1); + event = status & possible_status; + if (!event) { + dev_dbg(i2c_dev->dev, + "spurious evt irq (status=0x%08x, ien=0x%08x)\n", + status, ien); + return IRQ_NONE; + } + + /* Start condition generated */ + if (event & STM32F4_I2C_SR1_SB) + stm32f4_i2c_write_byte(i2c_dev, msg->addr); + + /* I2C Address sent */ + if (event & STM32F4_I2C_SR1_ADDR) { + if (msg->addr & I2C_M_RD) + stm32f4_i2c_handle_rx_addr(i2c_dev); + else + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); + + /* + * Enable buffer interrupts for RX not empty and TX empty + * events + */ + cr2 |= STM32F4_I2C_CR2_ITBUFEN; + writel_relaxed(cr2, i2c_dev->base + STM32F4_I2C_CR2); + } + + /* TX empty */ + if ((event & STM32F4_I2C_SR1_TXE) && !(msg->addr & I2C_M_RD)) + stm32f4_i2c_handle_write(i2c_dev); + + /* RX not empty */ + if ((event & STM32F4_I2C_SR1_RXNE) && (msg->addr & I2C_M_RD)) + stm32f4_i2c_handle_read(i2c_dev); + + /* + * The BTF (Byte Transfer finished) event occurs when: + * - in reception : a new byte is received in the shift register + * but the previous byte has not been read yet from data register + * - in transmission: a new byte should be sent but the data register + * has not been written yet + */ + if (event & STM32F4_I2C_SR1_BTF) { + if (msg->addr & I2C_M_RD) + stm32f4_i2c_handle_rx_done(i2c_dev); + else + stm32f4_i2c_handle_write(i2c_dev); + } + + return IRQ_HANDLED; +} + +/** + * stm32f4_i2c_isr_error() - Interrupt routine for I2C bus error + * @irq: interrupt number + * @data: Controller's private data + */ +static irqreturn_t stm32f4_i2c_isr_error(int irq, void *data) +{ + struct stm32f4_i2c_dev *i2c_dev = data; + struct stm32f4_i2c_msg *msg = &i2c_dev->msg; + void __iomem *reg; + u32 status; + + status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1); + + /* Arbitration lost */ + if (status & STM32F4_I2C_SR1_ARLO) { + status &= ~STM32F4_I2C_SR1_ARLO; + writel_relaxed(status, i2c_dev->base + STM32F4_I2C_SR1); + msg->result = -EAGAIN; + } + + /* + * Acknowledge failure: + * In master transmitter mode a Stop must be generated by software + */ + if (status & STM32F4_I2C_SR1_AF) { + if (!(msg->addr & I2C_M_RD)) { + reg = i2c_dev->base + STM32F4_I2C_CR1; + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); + } + status &= ~STM32F4_I2C_SR1_AF; + writel_relaxed(status, i2c_dev->base + STM32F4_I2C_SR1); + msg->result = -EIO; + } + + /* Bus error */ + if (status & STM32F4_I2C_SR1_BERR) { + status &= ~STM32F4_I2C_SR1_BERR; + writel_relaxed(status, i2c_dev->base + STM32F4_I2C_SR1); + msg->result = -EIO; + } + + stm32f4_i2c_disable_irq(i2c_dev); + complete(&i2c_dev->complete); + + return IRQ_HANDLED; +} + +/** + * stm32f4_i2c_xfer_msg() - Transfer a single I2C message + * @i2c_dev: Controller's private data + * @msg: I2C message to transfer + * @is_first: first message of the sequence + * @is_last: last message of the sequence + */ +static int stm32f4_i2c_xfer_msg(struct stm32f4_i2c_dev *i2c_dev, + struct i2c_msg *msg, bool is_first, + bool is_last) +{ + struct stm32f4_i2c_msg *f4_msg = &i2c_dev->msg; + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR1; + unsigned long timeout; + u32 mask; + int ret; + + f4_msg->addr = i2c_8bit_addr_from_msg(msg); + f4_msg->buf = msg->buf; + f4_msg->count = msg->len; + f4_msg->result = 0; + f4_msg->stop = is_last; + + reinit_completion(&i2c_dev->complete); + + /* Enable events and errors interrupts */ + mask = STM32F4_I2C_CR2_ITEVTEN | STM32F4_I2C_CR2_ITERREN; + stm32f4_i2c_set_bits(i2c_dev->base + STM32F4_I2C_CR2, mask); + + if (is_first) { + ret = stm32f4_i2c_wait_free_bus(i2c_dev); + if (ret) + return ret; + + /* START generation */ + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START); + } + + timeout = wait_for_completion_timeout(&i2c_dev->complete, + i2c_dev->adap.timeout); + ret = f4_msg->result; + + if (!timeout) + ret = -ETIMEDOUT; + + return ret; +} + +/** + * stm32f4_i2c_xfer() - Transfer combined I2C message + * @i2c_adap: Adapter pointer to the controller + * @msgs: Pointer to data to be written. + * @num: Number of messages to be executed + */ +static int stm32f4_i2c_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], + int num) +{ + struct stm32f4_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap); + int ret, i; + + ret = clk_enable(i2c_dev->clk); + if (ret) { + dev_err(i2c_dev->dev, "Failed to enable clock\n"); + return ret; + } + + for (i = 0; i < num && !ret; i++) + ret = stm32f4_i2c_xfer_msg(i2c_dev, &msgs[i], i == 0, + i == num - 1); + + clk_disable(i2c_dev->clk); + + return (ret < 0) ? ret : num; +} + +static u32 stm32f4_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm stm32f4_i2c_algo = { + .master_xfer = stm32f4_i2c_xfer, + .functionality = stm32f4_i2c_func, +}; + +static int stm32f4_i2c_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct stm32f4_i2c_dev *i2c_dev; + struct resource *res; + u32 irq_event, irq_error, clk_rate; + struct i2c_adapter *adap; + struct reset_control *rst; + int ret; + + i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); + if (!i2c_dev) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + i2c_dev->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(i2c_dev->base)) + return PTR_ERR(i2c_dev->base); + + irq_event = irq_of_parse_and_map(np, 0); + if (!irq_event) { + dev_err(&pdev->dev, "IRQ event missing or invalid\n"); + return -EINVAL; + } + + irq_error = irq_of_parse_and_map(np, 1); + if (!irq_error) { + dev_err(&pdev->dev, "IRQ error missing or invalid\n"); + return -EINVAL; + } + + i2c_dev->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(i2c_dev->clk)) { + dev_err(&pdev->dev, "Error: Missing controller clock\n"); + return PTR_ERR(i2c_dev->clk); + } + ret = clk_prepare_enable(i2c_dev->clk); + if (ret) { + dev_err(i2c_dev->dev, "Failed to prepare_enable clock\n"); + return ret; + } + + rst = devm_reset_control_get_exclusive(&pdev->dev, NULL); + if (IS_ERR(rst)) { + dev_err(&pdev->dev, "Error: Missing controller reset\n"); + ret = PTR_ERR(rst); + goto clk_free; + } + reset_control_assert(rst); + udelay(2); + reset_control_deassert(rst); + + i2c_dev->speed = STM32_I2C_SPEED_STANDARD; + ret = of_property_read_u32(np, "clock-frequency", &clk_rate); + if (!ret && clk_rate >= 400000) + i2c_dev->speed = STM32_I2C_SPEED_FAST; + + i2c_dev->dev = &pdev->dev; + + ret = devm_request_irq(&pdev->dev, irq_event, stm32f4_i2c_isr_event, 0, + pdev->name, i2c_dev); + if (ret) { + dev_err(&pdev->dev, "Failed to request irq event %i\n", + irq_event); + goto clk_free; + } + + ret = devm_request_irq(&pdev->dev, irq_error, stm32f4_i2c_isr_error, 0, + pdev->name, i2c_dev); + if (ret) { + dev_err(&pdev->dev, "Failed to request irq error %i\n", + irq_error); + goto clk_free; + } + + ret = stm32f4_i2c_hw_config(i2c_dev); + if (ret) + goto clk_free; + + adap = &i2c_dev->adap; + i2c_set_adapdata(adap, i2c_dev); + snprintf(adap->name, sizeof(adap->name), "STM32 I2C(%pa)", &res->start); + adap->owner = THIS_MODULE; + adap->timeout = 2 * HZ; + adap->retries = 0; + adap->algo = &stm32f4_i2c_algo; + adap->dev.parent = &pdev->dev; + adap->dev.of_node = pdev->dev.of_node; + + init_completion(&i2c_dev->complete); + + ret = i2c_add_adapter(adap); + if (ret) + goto clk_free; + + platform_set_drvdata(pdev, i2c_dev); + + clk_disable(i2c_dev->clk); + + dev_info(i2c_dev->dev, "STM32F4 I2C driver registered\n"); + + return 0; + +clk_free: + clk_disable_unprepare(i2c_dev->clk); + return ret; +} + +static int stm32f4_i2c_remove(struct platform_device *pdev) +{ + struct stm32f4_i2c_dev *i2c_dev = platform_get_drvdata(pdev); + + i2c_del_adapter(&i2c_dev->adap); + + clk_unprepare(i2c_dev->clk); + + return 0; +} + +static const struct of_device_id stm32f4_i2c_match[] = { + { .compatible = "st,stm32f4-i2c", }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm32f4_i2c_match); + +static struct platform_driver stm32f4_i2c_driver = { + .driver = { + .name = "stm32f4-i2c", + .of_match_table = stm32f4_i2c_match, + }, + .probe = stm32f4_i2c_probe, + .remove = stm32f4_i2c_remove, +}; + +module_platform_driver(stm32f4_i2c_driver); + +MODULE_AUTHOR("M'boumba Cedric Madianga <cedric.madianga@gmail.com>"); +MODULE_DESCRIPTION("STMicroelectronics STM32F4 I2C driver"); +MODULE_LICENSE("GPL v2"); |