Hi Uwe, Thanks for your comments. Please see below my answers and one question regarding duty cycle: 2016-12-23 10:00 GMT+01:00 Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>: > Hello, > > On Thu, Dec 22, 2016 at 02:35:01PM +0100, M'boumba Cedric Madianga wrote: >> This patch adds support for the STM32F4 I2C controller. >> >> Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx> >> --- >> drivers/i2c/busses/Kconfig | 10 + >> drivers/i2c/busses/Makefile | 1 + >> drivers/i2c/busses/i2c-stm32f4.c | 896 +++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 907 insertions(+) >> create mode 100644 drivers/i2c/busses/i2c-stm32f4.c >> >> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig >> index 0cdc844..2719208 100644 >> --- a/drivers/i2c/busses/Kconfig >> +++ b/drivers/i2c/busses/Kconfig >> @@ -886,6 +886,16 @@ 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 1c1bac8..a2c6ff5 100644 >> --- a/drivers/i2c/busses/Makefile >> +++ b/drivers/i2c/busses/Makefile >> @@ -85,6 +85,7 @@ 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..ca11dee >> --- /dev/null >> +++ b/drivers/i2c/busses/i2c-stm32f4.c >> @@ -0,0 +1,896 @@ >> +/* >> + * 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 >> + * Author: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx> >> + * >> + * This driver is based on 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)) > > ((n) & STM32F4_I2C_CR2_FREQ_MASK) > > should be enough. You are right. I will fix it in the V8. > >> +#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)) > > ditto ok > >> +#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 2U >> +#define STM32F4_I2C_MAX_FREQ 42U >> +#define HZ_TO_MHZ 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 >> + * @scl_period: SCL low/high period in microsecond >> + * @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 > > s/Khz/ kHz/ Good point. Thanks > >> + */ >> +struct stm32f4_i2c_timings { >> + u32 duty; >> + u32 scl_period; >> + u32 mul_ccr; >> + u32 min_ccr; >> +}; >> + >> +/** >> + * 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; > > You bought the argument about alignment of = in stm32f4_i2c_driver. The > same logic applies here. ok > >> +}; >> + >> +/** >> + * 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 only supported >> + * @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; >> + struct stm32f4_i2c_msg msg; >> +}; > > ditto ok > >> + >> +/* >> + * In standard mode: >> + * SCL high period = SCL low period = CCR * I2C CLK period >> + * So, CCR = SCL period * I2C CLK frequency > > is "SCL period" the same as "SCL low period"? I2C CLK frequency is the > input clk? If so, it's confusing that it has I2C in its name. The > reference manual calls it PCLK1 (parent clock?). SCL high period = SCL low period I2C CLK frequency = I2C parent clock frequency so I will add this precision in the V8 > >> + * In fast mode: >> + * DUTY = 0: Fast mode tlow/thigh = 2 >> + * DUTY = 1: Fast mode tlow/thigh = 16/9 >> + * If Duty = 0; SCL high period = 1 * CCR * I2C CLK period >> + * SCL low period = 2 * CCR * I2C CLK period >> + * If Duty = 1; SCL high period = 9 * CCR * I2C CLK period >> + * SCL low period = 16 * CCR * I2C CLK period > > I'd drop the first two lines about the proportions > >> + * >> + * Note that Duty has to bet set to reach 400khz in Fast mode > > s/khz/ kHz/ Ok. Thanks. > > I don't understand why DUTY is required to reach 400 kHz. Given a parent > freq of 30 MHz, with CCR = 25 and DUTY = 0 we have: > > t_high = 25 * 33.333 ns = 833.333 ns > t_low = 2 * 25 * 33.333 ns = 1666.667 ns > > then t_high and t_low satisfy the i2c bus specification > (t_low > 1300 ns, t_high > 600 ns) and we have t_low + t_high = 2500 ns > = 1 / 400 kHz. > > Where is the error? Hum ok you are right. I was a bad interpretation of the datasheet. So now it is clearer. Thanks for that. I will correct and improve my comments in the V8. > >> + * So, in order to cover both SCL high/low with Duty = 1, >> + * CCR = 16 * SCL period * I2C CLK frequency > > I don't get that. Actually you need to use low + high, so > CCR = parentrate / (25 * 400 kHz), right? With your new inputs above, I think I could use a simpler implementation: CCR = scl_high_period * parent_rate with scl_high_period = 5 µs in standard mode to reach 100khz and scl_high_period = 1 µs in fast mode to reach 400khz with 1/2 or 16/9 duty cycle. So, I am wondering if I have to let the customer setting the duty cycle in the DT for example with "st,duty=0" or "st,duty=1" property (0 for 1/2 and 1 for 16/9). Or perhaps the best option it to use a default value. What is your feeling regarding this point ? > >> + * >> + * Please note that the minimum allowed value is 0x04, except in FAST DUTY mode >> + * where the minimum allowed value is 0x01 >> + */ >> +static struct stm32f4_i2c_timings i2c_timings[] = { >> + [STM32F4_I2C_SPEED_STANDARD] = { >> + .mul_ccr = 1, >> + .min_ccr = 4, >> + .duty = 0, >> + .scl_period = 5, >> + }, >> + [STM32F4_I2C_SPEED_FAST] = { >> + .mul_ccr = 16, >> + .min_ccr = 1, >> + .duty = 1, >> + .scl_period = 2, >> + }, >> +}; >> + >> +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; >> + u32 val; >> + >> + val = readl_relaxed(reg); >> + writel_relaxed(val | STM32F4_I2C_CR1_SWRST, reg); >> + writel_relaxed(val, 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 void stm32f4_i2c_set_periph_clk_freq(struct stm32f4_i2c_dev *i2c_dev) >> +{ >> + u32 clk_rate, cr2, freq; >> + >> + /* >> + * The minimum allowed frequency is 2 MHz, the maximum frequency is >> + * limited by the maximum APB frequency 42 MHz >> + */ >> + cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2); >> + cr2 &= ~STM32F4_I2C_CR2_FREQ_MASK; >> + clk_rate = clk_get_rate(i2c_dev->clk); >> + freq = DIV_ROUND_UP(clk_rate, HZ_TO_MHZ); >> + freq = clamp(freq, STM32F4_I2C_MIN_FREQ, STM32F4_I2C_MAX_FREQ); >> + cr2 |= STM32F4_I2C_CR2_FREQ(freq); >> + writel_relaxed(cr2, i2c_dev->base + STM32F4_I2C_CR2); > > Last round I suggested error checking here instead of silent clamping. Ok > >> +} >> + >> +static void stm32f4_i2c_set_rise_time(struct stm32f4_i2c_dev *i2c_dev) >> +{ >> + u32 trise, freq, cr2; >> + >> + /* >> + * 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 09h.(1000 ns / 125 ns = 8 + 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 03h.(300 ns / 125 ns = 2 + 1) >> + * So, for I2C fast mode TRISE = FREQ[5:0] * 300 / 1000 + 1 >> + */ >> + >> + cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2); >> + freq = cr2 & STM32F4_I2C_CR2_FREQ_MASK; >> + >> + if (i2c_dev->speed == STM32F4_I2C_SPEED_STANDARD) >> + trise = freq + 1; >> + else >> + trise = freq * 300 / 1000 + 1; > > if freq is big such that freq * 300 overflows does this result in a > wrong result, or does the compiler optimize correctly? For sure the compiler will never exceeds u32 max value > >> + 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) >> +{ >> + struct stm32f4_i2c_timings *t = &i2c_timings[i2c_dev->speed]; >> + u32 cr2, ccr, freq, val; >> + >> + ccr = readl_relaxed(i2c_dev->base + STM32F4_I2C_CCR); >> + ccr &= ~(STM32F4_I2C_CCR_FS | STM32F4_I2C_CCR_DUTY | >> + STM32F4_I2C_CCR_CCR_MASK); >> + >> + /* >> + * Please see the comments above regarding i2c_timings[] declaration >> + * to understand the below calculation >> + */ >> + cr2 = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2); >> + freq = cr2 & STM32F4_I2C_CR2_FREQ_MASK; >> + val = freq * t->scl_period * 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); > > This is the first write to STM32F4_I2C_CR1, right? So the state from the > bootloader leaks here. This probably works most of the time, but if it > makes problems later, that's hard to debug. Also, what if the bootloader > already did some i2c transfers and kept the PE bit 1? I read in the > manual that PE must be 0 for some things. So this only works most of the > time. The first thing I do before configuring I2C device is to clear PE bit in order to disable I2C. In that way, all previous config will be erased by the new one. > >> +} >> + >> +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"); > > drop error message please or degrade to dev_debug ok I will use a dev_dbg message > >> + 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 & 0xff; >> + 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 = i2c_dev->base + STM32F4_I2C_CR2; >> + >> + 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 RXNE/TXE 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 >> + */ >> +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; >> + 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_msg *msg = &i2c_dev->msg; >> + void __iomem *reg; >> + u32 mask; >> + int i; >> + >> + switch (msg->count) { >> + case 2: >> + reg = i2c_dev->base + STM32F4_I2C_CR1; >> + /* Generate STOP or repeated Start */ >> + if (msg->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 events and error interrupts */ >> + 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_msg *msg = &i2c_dev->msg; >> + void __iomem *reg; >> + >> + 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, clear ADDR flag and generate STOP or RepSTART >> + */ >> + reg = i2c_dev->base + STM32F4_I2C_CR1; >> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_ACK); >> + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); >> + if (msg->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 set POS >> + */ >> + 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); >> + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); >> + break; >> + >> + default: >> + /* N-byte reception: Enable ACK */ >> + reg = i2c_dev->base + STM32F4_I2C_CR1; >> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_ACK); >> + readl_relaxed(i2c_dev->base + STM32F4_I2C_SR2); >> + break; >> + } >> +} > > This is still not really understandable. I have already added some comments from datasheet to explain the different cases. I don't see how I could be more understandable as it is clearly the hardware way of working... > >> + >> +/** >> + * 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; >> + void __iomem *reg; >> + u32 status, possible_status, ien; >> + int flag; >> + >> + ien = readl_relaxed(i2c_dev->base + STM32F4_I2C_CR2); >> + ien &= STM32F4_I2C_CR2_IRQ_MASK; >> + possible_status = 0; > > This can already be done when declaring possible_status. Ok. > >> + >> + /* 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; >> + } >> + >> + status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1); >> + >> + if (!(status & possible_status)) { >> + dev_dbg(i2c_dev->dev, >> + "spurious evt irq (status=0x%08x, ien=0x%08x)\n", >> + status, ien); >> + return IRQ_NONE; >> + } >> + >> + while (status & possible_status) { >> + /* Use __fls() to check error bits first */ >> + flag = __fls(status & possible_status); >> + >> + switch (1 << flag) { >> + case STM32F4_I2C_SR1_SB: >> + stm32f4_i2c_write_byte(i2c_dev, msg->addr); >> + break; >> + >> + case 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 RXNE/TXE events */ >> + reg = i2c_dev->base + STM32F4_I2C_CR2; >> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR2_ITBUFEN); >> + possible_status |= STM32F4_I2C_SR1_ITBUFEN_MASK; >> + break; >> + >> + case STM32F4_I2C_SR1_BTF: >> + if (msg->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 irq unhandled: status=0x%08x)\n", >> + status); >> + return IRQ_NONE; >> + } >> + status &= ~(1 << flag); >> + } > > I wouldn't do this in a loop. Just do: > > if (status & STM32F4_I2C_SR1_SB) { > ... > } > > if (status & ...) { > > } ok but I would prefer something like that: flag = status & possible_status if (flag & STM32F4_I2C_SR1_SB) { ... } if (flag & ...) { } > > Then it's obvious by reading the code in which order they are handled > without the need to check the definitions. Do you really need to jugle > with possible_status? I think I have to use possible_status as some events could occur whereas the corresponding interrupt is disabled. For example, for a 2 byte-reception, we don't have to take into accout RXNE event so the corresponding interrupt is disabled. If I don't check possible_status, I will call stm32f4_i2c_handle_read() for nothing and generates unneeded registers accesses. > >> + >> + 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, 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; >> + >> + status = readl_relaxed(i2c_dev->base + STM32F4_I2C_SR1); >> + >> + if (!(status & possible_status)) { >> + dev_dbg(i2c_dev->dev, >> + "spurious err it (status=0x%08x, ien=0x%08x)\n", >> + status, ien); >> + return IRQ_NONE; >> + } >> + >> + /* Use __fls() to check error bits first */ >> + flag = __fls(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); >> + msg->result = -EIO; >> + break; >> + >> + case STM32F4_I2C_SR1_ARLO: >> + reg = i2c_dev->base + STM32F4_I2C_SR1; >> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_SR1_ARLO); >> + msg->result = -EAGAIN; >> + break; >> + >> + case STM32F4_I2C_SR1_AF: >> + reg = i2c_dev->base + STM32F4_I2C_CR1; >> + stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_STOP); >> + msg->result = -EIO; >> + break; >> + >> + default: >> + dev_err(i2c_dev->dev, >> + "err it unhandled: status=0x%08x)\n", status); >> + return IRQ_NONE; >> + } > > You only check a single irq flag here. Yes only the first error could be reported to the i2c clients via msg->result that's why I don't check all errors. Moreover, as soon as an error occurs, the I2C device is reset. > >> + >> + stm32f4_i2c_soft_reset(i2c_dev); >> + 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; >> + >> + /* Disable PEC position Ack */ >> + stm32f4_i2c_clr_bits(reg, STM32F4_I2C_CR1_POS); > > This is the only place mentioning PEC. Should this be about POS instead? Yes you are right. Thanks > >> + >> + 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; >> + } >> + >> + 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 : num; >> +} >> + >> +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 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(i2c_dev->clk); >> + if (ret) { >> + dev_err(i2c_dev->dev, "Failed to prepare clock\n"); >> + return ret; >> + } >> + >> + rst = devm_reset_control_get(&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 = STM32F4_I2C_SPEED_STANDARD; >> + ret = of_property_read_u32(np, "clock-frequency", &clk_rate); >> + if (!ret && clk_rate >= 40000) >> + i2c_dev->speed = STM32F4_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); > > Starting here this irq might trigger. Can this happen? If so, > stm32f4_i2c_isr_event is called without the adapter being registered. > Probably not an issue as the controller was just reset. No irq could be triggered as after resett, the I2C is not enable as PE bit = 0. > >> + 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; >> + } >> + >> + 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); >> + >> + dev_info(i2c_dev->dev, "STM32F4 I2C driver registered\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@xxxxxxxxx>"); >> +MODULE_DESCRIPTION("STMicroelectronics STM32F4 I2C driver"); >> +MODULE_LICENSE("GPL v2"); >> -- >> 1.9.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
