[PATCH v3 2/5] i2c: Add STM32F4 I2C driver
Wolfram Sang
wsa at the-dreams.de
Fri Jul 22 00:02:20 PDT 2016
Hi,
thanks for this contribution! Looks mostly good, some comments, though.
On Mon, Jun 20, 2016 at 06:22:48PM +0200, M'boumba Cedric Madianga wrote:
> This patch adds support for the STM32F4 I2C controller.
>
> Signed-off-by: M'boumba Cedric Madianga <cedric.madianga at gmail.com>
> ---
> drivers/i2c/busses/Kconfig | 10 +
> drivers/i2c/busses/Makefile | 1 +
> drivers/i2c/busses/i2c-stm32f4.c | 863 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 874 insertions(+)
> create mode 100644 drivers/i2c/busses/i2c-stm32f4.c
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index faa8e68..805acf6 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -873,6 +873,16 @@ config I2C_ST
> This driver can also be built as module. If so, the module
> will be called i2c-st.
>
> +config I2C_STM32F4
> + tristate "STMicroelectronics STM32F4 I2C support"
> + depends on ARCH_STM32
|| COMPILE_TEST?
> + help
> + Enable this option to add support for STM32 I2C controller embedded
> + in STM32F4 SoCs.
> +
> + This driver can also be built as module. If so, the module
> + will be called i2c-stm32f4.
> +
> config I2C_STU300
> tristate "ST Microelectronics DDC I2C interface"
> depends on MACH_U300
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 37f2819..2ac0eb2 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_I2C_SH_MOBILE) += i2c-sh_mobile.o
> obj-$(CONFIG_I2C_SIMTEC) += i2c-simtec.o
> obj-$(CONFIG_I2C_SIRF) += i2c-sirf.o
> obj-$(CONFIG_I2C_ST) += i2c-st.o
> +obj-$(CONFIG_I2C_STM32F4) += i2c-stm32f4.o
> obj-$(CONFIG_I2C_STU300) += i2c-stu300.o
> obj-$(CONFIG_I2C_SUN6I_P2WI) += i2c-sun6i-p2wi.o
> obj-$(CONFIG_I2C_TEGRA) += i2c-tegra.o
> diff --git a/drivers/i2c/busses/i2c-stm32f4.c b/drivers/i2c/busses/i2c-stm32f4.c
> new file mode 100644
> index 0000000..652d4bf
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-stm32f4.c
> @@ -0,0 +1,863 @@
> +/*
> + * Driver for STMicroelectronics STM32 I2C controller
> + *
> + * Copyright (C) M'boumba Cedric Madianga 2015
> + * Author: M'boumba Cedric Madianga <cedric.madianga at gmail.com>
> + *
> + * This driver is based on st-i2c.c
i2c-st.c ?
> + *
> + * License terms: GNU General Public License (GPL), version 2
> + */
> +
> +#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>
> +
> +/* 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_SWRST BIT(15)
> +#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))
> +
> +/* STM32F4 I2C Filter */
> +#define STM32F4_I2C_FLTR_DNF_MASK GENMASK(3, 0)
> +#define STM32F4_I2C_FLTR_DNF(n) ((n & STM32F4_I2C_FLTR_DNF_MASK))
> +#define STM32F4_I2C_FLTR_ANOFF BIT(4)
> +
> +#define STM32F4_I2C_MIN_FREQ 2
> +#define STM32F4_I2C_MAX_FREQ 42
> +#define FAST_MODE_MAX_RISE_TIME 1000
> +#define STD_MODE_MAX_RISE_TIME 300
> +#define MHZ_TO_HZ 1000000
> +
> +enum stm32f4_i2c_speed {
> + STM32F4_I2C_SPEED_STANDARD, /* 100 kHz */
> + STM32F4_I2C_SPEED_FAST, /* 400 kHz */
> + STM32F4_I2C_SPEED_END,
> +};
> +
> +/**
> + * struct stm32f4_i2c_timings - per-Mode tuning parameters
> + * @duty: Fast mode duty cycle
> + * @mul_ccr: Value to be multiplied to CCR to reach 100Khz/400Khz SCL frequency
> + * @min_ccr: Minimum clock ctrl reg value to reach 100Khz/400Khz SCL frequency
> + */
> +struct stm32f4_i2c_timings {
> + u32 rate;
> + u32 duty;
> + u32 mul_ccr;
> + u32 min_ccr;
> +};
> +
> +/**
> + * struct stm32f4_i2c_client - 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_client {
I think the name is a little misleading. Check 'struct i2c_client' as a
comparison. A more comprehensible name might be 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
> + * @irq_event: interrupt event line for the controller
> + * @irq_error: interrupt error line for the controller
> + * @clk: hw i2c clock
> + * speed: I2C clock frequency of the controller. Standard or Fast only supported
> + * @client: I2C transfer information
> + * @rst: I2C reset line
> + */
> +struct stm32f4_i2c_dev {
> + struct i2c_adapter adap;
> + struct device *dev;
> + void __iomem *base;
> + struct completion complete;
> + int irq_event;
> + int irq_error;
> + struct clk *clk;
> + int speed;
> + struct stm32f4_i2c_client client;
> + struct reset_control *rst;
No need to store reset_control. You just use it in probe.
> +};
> +
> +static struct stm32f4_i2c_timings i2c_timings[] = {
> + [STM32F4_I2C_SPEED_STANDARD] = {
> + .mul_ccr = 1,
> + .min_ccr = 4,
> + .duty = 0,
> + },
> + [STM32F4_I2C_SPEED_FAST] = {
> + .mul_ccr = 16,
> + .min_ccr = 1,
> + .duty = 1,
> + },
> +};
> +
> +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_soft_reset(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR1;
> +
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_SWRST);
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_SWRST);
> +}
> +
> +static void stm32f4_i2c_disable_it(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 void stm32f4_i2c_set_periph_clk_freq(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + u32 clk_rate, cr2, freq;
> +
> + cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2);
> + cr2 &= ~STM32F4_I2C_CR2_FREQ_MASK;
> +
> + clk_rate = clk_get_rate(i2c_dev->clk);
> + freq = clk_rate / MHZ_TO_HZ;
> +
> + if (freq > STM32F4_I2C_MAX_FREQ)
> + freq = STM32F4_I2C_MAX_FREQ;
> + if (freq < STM32F4_I2C_MIN_FREQ)
> + freq = STM32F4_I2C_MIN_FREQ;
clamp() to enforce the range?
> +
> + cr2 |= STM32F4_I2C_CR2_FREQ(freq);
> + writel_relaxed(cr2, i2c_dev->base + STM32F4_I2C_CR2);
> +}
> +
> +static void stm32f4_i2c_set_rise_time(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + u32 trise, freq, cr2, val;
> +
> + cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2);
> + freq = cr2 & STM32F4_I2C_CR2_FREQ_MASK;
> +
> + trise = readl_relaxed(i2c_dev->base + STM32F4_I2C_TRISE);
> + trise &= ~STM32F4_I2C_TRISE_VALUE_MASK;
> +
> + /* Maximum rise time computation */
> + if (i2c_dev->speed == STM32F4_I2C_SPEED_STANDARD) {
> + trise |= STM32F4_I2C_TRISE_VALUE((freq + 1));
> + } else {
> + val = freq * FAST_MODE_MAX_RISE_TIME / STD_MODE_MAX_RISE_TIME;
> + trise |= STM32F4_I2C_TRISE_VALUE((val + 1));
> + }
> +
> + writel_relaxed(trise, i2c_dev->base + STM32F4_I2C_TRISE);
> +}
> +
> +static void stm32f4_i2c_set_speed_mode(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + struct stm32f4_i2c_timings *t = &i2c_timings[i2c_dev->speed];
> + u32 ccr, clk_rate;
> + int val;
> +
> + ccr = readl_relaxed(i2c_dev->base + STM32F4_I2C_CCR);
> + ccr &= ~(STM32F4_I2C_CCR_FS | STM32F4_I2C_CCR_DUTY |
> + STM32F4_I2C_CCR_CCR_MASK);
> +
> + clk_rate = clk_get_rate(i2c_dev->clk);
> + val = clk_rate / MHZ_TO_HZ * t->mul_ccr;
> + if (val < t->min_ccr)
> + val = t->min_ccr;
> + ccr |= STM32F4_I2C_CCR_CCR(val);
> +
> + if (t->duty)
> + ccr |= STM32F4_I2C_CCR_FS | STM32F4_I2C_CCR_DUTY;
> +
> + writel_relaxed(ccr, i2c_dev->base + STM32F4_I2C_CCR);
> +}
> +
> +static void stm32f4_i2c_set_filter(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + u32 filter;
> +
> + /* Enable analog noise filter and disable digital noise filter */
> + filter = readl_relaxed(i2c_dev->base + STM32F4_I2C_FLTR);
> + filter &= ~(STM32F4_I2C_FLTR_ANOFF | STM32F4_I2C_FLTR_DNF_MASK);
> + writel_relaxed(filter, i2c_dev->base + STM32F4_I2C_FLTR);
> +}
> +
> +/**
> + * stm32f4_i2c_hw_config() - Prepare I2C block
> + * @i2c_dev: Controller's private data
> + */
> +static void stm32f4_i2c_hw_config(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR1;
> +
> + /* Disable I2C */
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_PE);
> +
> + stm32f4_i2c_set_periph_clk_freq(i2c_dev);
> +
> + stm32f4_i2c_set_rise_time(i2c_dev);
> +
> + stm32f4_i2c_set_speed_mode(i2c_dev);
> +
> + stm32f4_i2c_set_filter(i2c_dev);
> +
> + /* Enable I2C */
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_PE);
> +}
> +
> +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_err(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_client *c = &i2c_dev->client;
> +
> + stm32f4_i2c_write_byte(i2c_dev, *c->buf++);
> + c->count--;
> +}
> +
> +static void stm32f4_i2c_read_msg(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + struct stm32f4_i2c_client *c = &i2c_dev->client;
> + u32 rbuf;
> +
> + rbuf = readl_relaxed(i2c_dev->base + STM32F4_I2C_DR);
> + *c->buf++ = (u8)rbuf & 0xff;
> + c->count--;
> +}
> +
> +static void stm32f4_i2c_terminate_xfer(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + struct stm32f4_i2c_client *c = &i2c_dev->client;
> + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2;
> +
> + stm32f4_i2c_disable_it(i2c_dev);
> +
> + reg = i2c_dev->base + STM32F4_I2C_CR1;
> + if (c->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_client *c = &i2c_dev->client;
> + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2;
> +
> + if (c->count) {
> + stm32f4_i2c_write_msg(i2c_dev);
> + if (!c->count) {
> + /* Disable BUF interrupt */
> + 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
> + */
> +static void stm32f4_i2c_handle_read(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + struct stm32f4_i2c_client *c = &i2c_dev->client;
> + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR2;
> +
> + switch (c->count) {
> + case 1:
> + stm32f4_i2c_disable_it(i2c_dev);
> + stm32f4_i2c_read_msg(i2c_dev);
> + complete(&i2c_dev->complete);
> + break;
> + case 2:
> + case 3:
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR2_ITBUFEN);
> + break;
> + default:
> + stm32f4_i2c_read_msg(i2c_dev);
> + }
> +}
> +
> +/**
> + * stm32f4_i2c_handle_rx_btf() - Handle byte transfer finished interrupt
> + * in case of read
> + * @i2c_dev: Controller's private data
> + */
> +static void stm32f4_i2c_handle_rx_btf(struct stm32f4_i2c_dev *i2c_dev)
> +{
> + struct stm32f4_i2c_client *c = &i2c_dev->client;
> + void __iomem *reg;
> + u32 mask;
> + int i;
> +
> + switch (c->count) {
> + case 2:
> + reg = i2c_dev->base + STM32F4_I2C_CR1;
> + /* Generate STOP or REPSTART */
> + if (c->stop)
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP);
> + else
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START);
> +
> + /* Read two last data bytes */
> + for (i = 2; i > 0; i--)
> + stm32f4_i2c_read_msg(i2c_dev);
> +
> + /* Disable EVT and ERR interrupt */
> + 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:
> + /* Enable ACK and read 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_client *c = &i2c_dev->client;
> + void __iomem *reg;
> + u32 sr2;
> +
> + switch (c->count) {
> + case 0:
> + stm32f4_i2c_terminate_xfer(i2c_dev);
> + /* Clear ADDR flag */
> + sr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2);
> + break;
> + case 1:
> + /*
> + * Single byte reception:
> + * Enable NACK, clear ADDR flag and generate STOP or RepSTART
> + */
> + reg = i2c_dev->base + STM32F4_I2C_CR1;
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK);
> + sr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2);
> + if (c->stop)
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP);
> + else
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START);
> + break;
> + case 2:
> + /*
> + * 2-byte reception:
> + * Enable NACK and PEC Position Ack and clear ADDR flag
> + */
> + reg = i2c_dev->base + STM32F4_I2C_CR1;
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK);
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_POS);
> + sr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2);
> + break;
> +
> + default:
> + /* N-byte reception: Enable ACK and clear ADDR flag */
> + reg = i2c_dev->base + STM32F4_I2C_CR1;
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_ACK);
> + sr2 = 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_client *c = &i2c_dev->client;
> + void __iomem *reg;
> + u32 real_status, possible_status, ien, sr2;
> + int flag;
> +
> + ien = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2);
> + ien &= STM32F4_I2C_CR2_IRQ_MASK;
> + possible_status = 0;
> +
> + /* Check possible status combinations */
> + if (ien & STM32F4_I2C_CR2_ITEVTEN) {
> + possible_status = STM32F4_I2C_SR1_ITEVTEN_MASK;
> + if (ien & STM32F4_I2C_CR2_ITBUFEN)
> + possible_status |= STM32F4_I2C_SR1_ITBUFEN_MASK;
> + }
> +
> + real_status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1);
> +
> + if (!(real_status & possible_status)) {
> + dev_dbg(i2c_dev->dev,
> + "spurious evt it (status=0x%08x, ien=0x%08x)\n",
> + real_status, ien);
> + return IRQ_NONE;
> + }
> +
> + /* Use __fls() to check error bits first */
> + flag = __fls(real_status & possible_status);
> +
> + switch (1 << flag) {
> + case STM32F4_I2C_SR1_SB:
> + stm32f4_i2c_write_byte(i2c_dev, c->addr);
> + break;
> +
> + case STM32F4_I2C_SR1_ADDR:
> + if (c->addr & I2C_M_RD)
> + stm32f4_i2c_handle_rx_addr(i2c_dev);
> + else
> + sr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2);
> +
> + /* Enable ITBUF interrupts */
> + reg = i2c_dev->base + STM32F4_I2C_CR2;
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR2_ITBUFEN);
> + break;
> +
> + case STM32F4_I2C_SR1_BTF:
> + if (c->addr & I2C_M_RD)
> + stm32f4_i2c_handle_rx_btf(i2c_dev);
> + else
> + stm32f4_i2c_handle_write(i2c_dev);
> + break;
> +
> + case STM32F4_I2C_SR1_TXE:
> + stm32f4_i2c_handle_write(i2c_dev);
> + break;
> +
> + case STM32F4_I2C_SR1_RXNE:
> + stm32f4_i2c_handle_read(i2c_dev);
> + break;
> +
> + default:
> + dev_err(i2c_dev->dev,
> + "evt it unhandled: status=0x%08x)\n", real_status);
> + return IRQ_NONE;
> + }
> +
> + 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_client *c = &i2c_dev->client;
> + void __iomem *reg;
> + u32 real_status, possible_status, ien;
> + int flag;
> +
> + ien = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2);
> + ien &= STM32F4_I2C_CR2_IRQ_MASK;
> + possible_status = 0;
> +
> + /* Check possible status combinations */
> + if (ien & STM32F4_I2C_CR2_ITERREN)
> + possible_status = STM32F4_I2C_SR1_ITERREN_MASK;
> +
> + real_status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1);
> +
> + if (!(real_status & possible_status)) {
> + dev_dbg(i2c_dev->dev,
> + "spurious err it (status=0x%08x, ien=0x%08x)\n",
> + real_status, ien);
> + return IRQ_NONE;
> + }
> +
> + /* Use __fls() to check error bits first */
> + flag = __fls(real_status & possible_status);
> +
> + switch (1 << flag) {
> + case STM32F4_I2C_SR1_BERR:
> + reg = i2c_dev->base + STM32F4_I2C_SR1;
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_SR1_BERR);
> + c->result = -EIO;
> + break;
> +
> + case STM32F4_I2C_SR1_ARLO:
> + reg = i2c_dev->base + STM32F4_I2C_SR1;
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_SR1_ARLO);
> + c->result = -EAGAIN;
> + break;
> +
> + case STM32F4_I2C_SR1_AF:
> + reg = i2c_dev->base + STM32F4_I2C_CR1;
> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP);
> + c->result = -EIO;
> + break;
> +
> + default:
> + dev_err(i2c_dev->dev,
> + "err it unhandled: status=0x%08x)\n", real_status);
> + return IRQ_NONE;
> + }
> +
> + stm32f4_i2c_soft_reset(i2c_dev);
> + stm32f4_i2c_disable_it(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_client *c = &i2c_dev->client;
> + void __iomem *reg = i2c_dev->base + STM32F4_I2C_CR1;
> + unsigned long timeout;
> + u32 mask;
> + int ret;
> +
> + c->addr = (u8)(msg->addr << 1);
> + c->addr |= (msg->flags & I2C_M_RD);
Use the shiny new "i2c_8bit_addr_from_msg()" for the last two lines.
> + c->buf = msg->buf;
> + c->count = msg->len;
> + c->result = 0;
> + c->stop = is_last;
> +
> + reinit_completion(&i2c_dev->complete);
> +
> + /* Enable ITEVT and ITERR 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 = c->result;
> +
> + /* Disable PEC position Ack */
> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_POS);
> +
> + if (!timeout) {
> + dev_err(i2c_dev->dev, "Access to slave 0x%x timed out\n",
> + c->addr >> 1);
I don't recommend writing err messages for timeouts. They regularly
happen, e.g. when an eeprom is doing a page write cycle.
> + 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;
> + }
> +
> + stm32f4_i2c_hw_config(i2c_dev);
> +
> + 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 : i;
> +}
> +
> +static u32 stm32f4_i2c_func(struct i2c_adapter *adap)
> +{
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static 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 clk_rate;
> + struct i2c_adapter *adap;
> + 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);
> +
> + i2c_dev->irq_event = irq_of_parse_and_map(np, 0);
> + if (!i2c_dev->irq_event) {
> + dev_err(&pdev->dev, "IRQ missing or invalid\n");
> + return -EINVAL;
> + }
> +
> + i2c_dev->irq_error = irq_of_parse_and_map(np, 1);
> + if (!i2c_dev->irq_error) {
> + dev_err(&pdev->dev, "IRQ 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(i2c_dev->clk);
> + if (ret) {
> + dev_err(i2c_dev->dev, "Failed to prepare clock\n");
> + return ret;
> + }
> +
> + i2c_dev->rst = devm_reset_control_get(&pdev->dev, NULL);
> + if (IS_ERR(i2c_dev->rst)) {
> + dev_err(&pdev->dev, "Error: Missing controller reset\n");
> + return PTR_ERR(i2c_dev->rst);
> + }
> + reset_control_assert(i2c_dev->rst);
> + udelay(2);
> + reset_control_deassert(i2c_dev->rst);
> +
> + i2c_dev->speed = STM32F4_I2C_SPEED_STANDARD;
> + ret = of_property_read_u32(np, "clock-frequency", &clk_rate);
> + if ((!ret) && (clk_rate == 400000))
> + i2c_dev->speed = STM32F4_I2C_SPEED_FAST;
> +
> + i2c_dev->dev = &pdev->dev;
> +
> + ret = devm_request_threaded_irq(&pdev->dev, i2c_dev->irq_event,
> + NULL, stm32f4_i2c_isr_event,
> + IRQF_ONESHOT, pdev->name, i2c_dev);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to request irq %i\n",
> + i2c_dev->irq_error);
> + goto clk_free;
> + }
> +
> + ret = devm_request_threaded_irq(&pdev->dev, i2c_dev->irq_error,
> + NULL, stm32f4_i2c_isr_error,
> + IRQF_ONESHOT, pdev->name, i2c_dev);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to request irq %i\n",
> + i2c_dev->irq_error);
> + 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) {
> + dev_err(&pdev->dev, "Failed to add adapter\n");
Please drop this messages. We have patches in i2c/for-next where the
core will report all errors.
> + goto clk_free;
> + }
> +
> + platform_set_drvdata(pdev, i2c_dev);
> +
> + dev_info(i2c_dev->dev, "STM32F4 I2C driver initialized\n");
> +
> + return 0;
> +
> +clk_free:
> + clk_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 at gmail.com>");
> +MODULE_DESCRIPTION("STMicroelectronics STM32F4 I2C driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.9.1
>
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