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Subject[PATCH v3 3/5] i2c: i2c-stm32f7: add driver
Date
This patch adds initial support for the STM32F7 I2C controller.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
Version history:
v3:
* Move stm32f7_i2c_match above stm32f7_i2c_driver
* of_device_get_match_data instead of of_match_device
* Improve I2C Speed DT gathering
* dev_err into dev_dbg for Arbitration loss
* Remove useless space aligned

v2:
* Remove st,i2c-timing binding usage
* Implement an I2C timings computation algorithm instead of
static values(bindings). Algorithm uses generic I2C SCL
Falling/Rising bindings and System clock to compute its timings.
---
---
drivers/i2c/busses/Kconfig | 10 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-stm32f7.c | 974 +++++++++++++++++++++++++++++++++++++++
3 files changed, 985 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-stm32f7.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 1006b23..97fc74b 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -920,6 +920,16 @@ config I2C_STM32F4
This driver can also be built as module. If so, the module
will be called i2c-stm32f4.

+config I2C_STM32F7
+ tristate "STMicroelectronics STM32F7 I2C support"
+ depends on ARCH_STM32 || COMPILE_TEST
+ help
+ Enable this option to add support for STM32 I2C controller embedded
+ in STM32F7 SoCs.
+
+ This driver can also be built as module. If so, the module
+ will be called i2c-stm32f7.
+
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 1b2fc81..7816a9f 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -91,6 +91,7 @@ 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-$(CONFIG_I2C_STM32F7) += i2c-stm32f7.o
obj-$(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-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
new file mode 100644
index 0000000..b3ab288
--- /dev/null
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -0,0 +1,974 @@
+/*
+ * Driver for STMicroelectronics STM32F7 I2C controller
+ *
+ * This I2C controller is described in the STM32F75xxx and STM32F74xxx Soc
+ * reference manual.
+ * Please see below a link to the documentation:
+ * http://www.st.com/resource/en/reference_manual/dm00124865.pdf
+ *
+ * Copyright (C) M'boumba Cedric Madianga 2017
+ * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
+ *
+ * This driver is based on i2c-stm32f4.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.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+
+#include "i2c-stm32.h"
+
+/* STM32F7 I2C registers */
+#define STM32F7_I2C_CR1 0x00
+#define STM32F7_I2C_CR2 0x04
+#define STM32F7_I2C_TIMINGR 0x10
+#define STM32F7_I2C_ISR 0x18
+#define STM32F7_I2C_ICR 0x1C
+#define STM32F7_I2C_RXDR 0x24
+#define STM32F7_I2C_TXDR 0x28
+
+/* STM32F7 I2C control 1 */
+#define STM32F7_I2C_CR1_ANFOFF BIT(12)
+#define STM32F7_I2C_CR1_ERRIE BIT(7)
+#define STM32F7_I2C_CR1_TCIE BIT(6)
+#define STM32F7_I2C_CR1_STOPIE BIT(5)
+#define STM32F7_I2C_CR1_NACKIE BIT(4)
+#define STM32F7_I2C_CR1_ADDRIE BIT(3)
+#define STM32F7_I2C_CR1_RXIE BIT(2)
+#define STM32F7_I2C_CR1_TXIE BIT(1)
+#define STM32F7_I2C_CR1_PE BIT(0)
+#define STM32F7_I2C_ALL_IRQ_MASK (STM32F7_I2C_CR1_ERRIE \
+ | STM32F7_I2C_CR1_TCIE \
+ | STM32F7_I2C_CR1_STOPIE \
+ | STM32F7_I2C_CR1_NACKIE \
+ | STM32F7_I2C_CR1_RXIE \
+ | STM32F7_I2C_CR1_TXIE)
+
+/* STM32F7 I2C control 2 */
+#define STM32F7_I2C_CR2_RELOAD BIT(24)
+#define STM32F7_I2C_CR2_NBYTES_MASK GENMASK(23, 16)
+#define STM32F7_I2C_CR2_NBYTES(n) (((n) & 0xff) << 16)
+#define STM32F7_I2C_CR2_NACK BIT(15)
+#define STM32F7_I2C_CR2_STOP BIT(14)
+#define STM32F7_I2C_CR2_START BIT(13)
+#define STM32F7_I2C_CR2_RD_WRN BIT(10)
+#define STM32F7_I2C_CR2_SADD7_MASK GENMASK(7, 1)
+#define STM32F7_I2C_CR2_SADD7(n) (((n) & 0x7f) << 1)
+
+/* STM32F7 I2C Interrupt Status */
+#define STM32F7_I2C_ISR_BUSY BIT(15)
+#define STM32F7_I2C_ISR_ARLO BIT(9)
+#define STM32F7_I2C_ISR_BERR BIT(8)
+#define STM32F7_I2C_ISR_TCR BIT(7)
+#define STM32F7_I2C_ISR_TC BIT(6)
+#define STM32F7_I2C_ISR_STOPF BIT(5)
+#define STM32F7_I2C_ISR_NACKF BIT(4)
+#define STM32F7_I2C_ISR_RXNE BIT(2)
+#define STM32F7_I2C_ISR_TXIS BIT(1)
+
+/* STM32F7 I2C Interrupt Clear */
+#define STM32F7_I2C_ICR_ARLOCF BIT(9)
+#define STM32F7_I2C_ICR_BERRCF BIT(8)
+#define STM32F7_I2C_ICR_STOPCF BIT(5)
+#define STM32F7_I2C_ICR_NACKCF BIT(4)
+
+/* STM32F7 I2C Timing */
+#define STM32F7_I2C_TIMINGR_PRESC(n) (((n) & 0xf) << 28)
+#define STM32F7_I2C_TIMINGR_SCLDEL(n) (((n) & 0xf) << 20)
+#define STM32F7_I2C_TIMINGR_SDADEL(n) (((n) & 0xf) << 16)
+#define STM32F7_I2C_TIMINGR_SCLH(n) (((n) & 0xff) << 8)
+#define STM32F7_I2C_TIMINGR_SCLL(n) ((n) & 0xff)
+
+#define STM32F7_I2C_MAX_LEN 0xff
+
+#define STM32F7_I2C_DNF_DEFAULT 0
+#define STM32F7_I2C_DNF_MAX 16
+
+#define STM32F7_I2C_ANALOG_FILTER_ENABLE 1
+#define STM32F7_I2C_ANALOG_FILTER_DELAY_MIN 50 /* ns */
+#define STM32F7_I2C_ANALOG_FILTER_DELAY_MAX 260 /* ns */
+
+#define STM32F7_I2C_RISE_TIME_DEFAULT 25 /* ns */
+#define STM32F7_I2C_FALL_TIME_DEFAULT 10 /* ns */
+
+#define STM32F7_PRESC_MAX BIT(4)
+#define STM32F7_SCLDEL_MAX BIT(4)
+#define STM32F7_SDADEL_MAX BIT(4)
+#define STM32F7_SCLH_MAX BIT(8)
+#define STM32F7_SCLL_MAX BIT(8)
+
+/**
+ * struct stm32f7_i2c_spec - private i2c specification timing
+ * @rate: I2C bus speed (Hz)
+ * @rate_min: 80% of I2C bus speed (Hz)
+ * @rate_max: 120% of I2C bus speed (Hz)
+ * @fall_max: Max fall time of both SDA and SCL signals (ns)
+ * @rise_max: Max rise time of both SDA and SCL signals (ns)
+ * @hddat_min: Min data hold time (ns)
+ * @vddat_max: Max data valid time (ns)
+ * @sudat_min: Min data setup time (ns)
+ * @l_min: Min low period of the SCL clock (ns)
+ * @h_min: Min high period of the SCL clock (ns)
+ */
+struct stm32f7_i2c_spec {
+ u32 rate;
+ u32 rate_min;
+ u32 rate_max;
+ u32 fall_max;
+ u32 rise_max;
+ u32 hddat_min;
+ u32 vddat_max;
+ u32 sudat_min;
+ u32 l_min;
+ u32 h_min;
+};
+
+/**
+ * struct stm32f7_i2c_setup - private I2C timing setup parameters
+ * @speed: I2C speed mode (standard, Fast Plus)
+ * @speed_freq: I2C speed frequency (Hz)
+ * @clock_src: I2C clock source frequency (Hz)
+ * @rise_time: Rise time (ns)
+ * @fall_time: Fall time (ns)
+ * @dnf: Digital filter coefficient (0-16)
+ * @analog_filter: Analog filter delay (On/Off)
+ */
+struct stm32f7_i2c_setup {
+ enum stm32_i2c_speed speed;
+ u32 speed_freq;
+ u32 clock_src;
+ u32 rise_time;
+ u32 fall_time;
+ u8 dnf;
+ bool analog_filter;
+};
+
+/**
+ * struct stm32f7_i2c_timings - private I2C output parameters
+ * @prec: Prescaler value
+ * @scldel: Data setup time
+ * @sdadel: Data hold time
+ * @sclh: SCL high period (master mode)
+ * @sclh: SCL low period (master mode)
+ */
+struct stm32f7_i2c_timings {
+ struct list_head node;
+ u8 presc;
+ u8 scldel;
+ u8 sdadel;
+ u8 sclh;
+ u8 scll;
+};
+
+/**
+ * struct stm32f7_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 stm32f7_i2c_msg {
+ u8 addr;
+ u32 count;
+ u8 *buf;
+ int result;
+ bool stop;
+};
+
+/**
+ * struct stm32f7_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, Fast or Fast+
+ * @msg: Pointer to data to be written
+ * @msg_num: number of I2C messages to be executed
+ * @msg_id: message identifiant
+ * @f7_msg: customized i2c msg for driver usage
+ * @setup: I2C timing input setup
+ * @timing: I2C computed timings
+ */
+struct stm32f7_i2c_dev {
+ struct i2c_adapter adap;
+ struct device *dev;
+ void __iomem *base;
+ struct completion complete;
+ struct clk *clk;
+ int speed;
+ struct i2c_msg *msg;
+ unsigned int msg_num;
+ unsigned int msg_id;
+ struct stm32f7_i2c_msg f7_msg;
+ struct stm32f7_i2c_setup *setup;
+ struct stm32f7_i2c_timings timing;
+};
+
+/**
+ * All these values are coming from I2C Specification, Version 6.0, 4th of
+ * April 2014.
+ *
+ * Table10. Characteristics of the SDA and SCL bus lines for Standard, Fast,
+ * and Fast-mode Plus I2C-bus devices
+ */
+static struct stm32f7_i2c_spec i2c_specs[] = {
+ [STM32_I2C_SPEED_STANDARD] = {
+ .rate = 100000,
+ .rate_min = 8000,
+ .rate_max = 120000,
+ .fall_max = 300,
+ .rise_max = 1000,
+ .hddat_min = 0,
+ .vddat_max = 3450,
+ .sudat_min = 250,
+ .l_min = 4700,
+ .h_min = 4000,
+ },
+ [STM32_I2C_SPEED_FAST] = {
+ .rate = 400000,
+ .rate_min = 320000,
+ .rate_max = 480000,
+ .fall_max = 300,
+ .rise_max = 300,
+ .hddat_min = 0,
+ .vddat_max = 900,
+ .sudat_min = 100,
+ .l_min = 1300,
+ .h_min = 600,
+ },
+ [STM32_I2C_SPEED_FAST_PLUS] = {
+ .rate = 1000000,
+ .rate_min = 800000,
+ .rate_max = 1200000,
+ .fall_max = 100,
+ .rise_max = 120,
+ .hddat_min = 0,
+ .vddat_max = 450,
+ .sudat_min = 50,
+ .l_min = 500,
+ .h_min = 260,
+ },
+};
+
+struct stm32f7_i2c_setup stm32f7_setup = {
+ .rise_time = STM32F7_I2C_RISE_TIME_DEFAULT,
+ .fall_time = STM32F7_I2C_FALL_TIME_DEFAULT,
+ .dnf = STM32F7_I2C_DNF_DEFAULT,
+ .analog_filter = STM32F7_I2C_ANALOG_FILTER_ENABLE,
+};
+
+static inline void stm32f7_i2c_set_bits(void __iomem *reg, u32 mask)
+{
+ writel_relaxed(readl_relaxed(reg) | mask, reg);
+}
+
+static inline void stm32f7_i2c_clr_bits(void __iomem *reg, u32 mask)
+{
+ writel_relaxed(readl_relaxed(reg) & ~mask, reg);
+}
+
+static int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
+ struct stm32f7_i2c_setup *setup,
+ struct stm32f7_i2c_timings *output)
+{
+ u32 p_prev = STM32F7_PRESC_MAX;
+ u32 i2cclk = DIV_ROUND_CLOSEST(NSEC_PER_SEC,
+ setup->clock_src);
+ u32 i2cbus = DIV_ROUND_CLOSEST(NSEC_PER_SEC,
+ setup->speed_freq);
+ u32 clk_error_prev = i2cbus;
+ u32 tsync;
+ u32 af_delay_min, af_delay_max;
+ u32 dnf_delay;
+ u32 clk_min, clk_max;
+ int sdadel_min, sdadel_max;
+ int scldel_min;
+ struct stm32f7_i2c_timings *v, *_v, *s;
+ struct list_head solutions;
+ u16 p, l, a, h;
+ int ret = 0;
+
+ if (setup->speed >= STM32_I2C_SPEED_END) {
+ dev_err(i2c_dev->dev, "speed out of bound {%d/%d}\n",
+ setup->speed, STM32_I2C_SPEED_END - 1);
+ return -EINVAL;
+ }
+
+ if ((setup->rise_time > i2c_specs[setup->speed].rise_max) ||
+ (setup->fall_time > i2c_specs[setup->speed].fall_max)) {
+ dev_err(i2c_dev->dev,
+ "timings out of bound Rise{%d>%d}/Fall{%d>%d}\n",
+ setup->rise_time, i2c_specs[setup->speed].rise_max,
+ setup->fall_time, i2c_specs[setup->speed].fall_max);
+ return -EINVAL;
+ }
+
+ if (setup->dnf > STM32F7_I2C_DNF_MAX) {
+ dev_err(i2c_dev->dev,
+ "DNF out of bound %d/%d\n",
+ setup->dnf, STM32F7_I2C_DNF_MAX);
+ return -EINVAL;
+ }
+
+ if (setup->speed_freq > i2c_specs[setup->speed].rate) {
+ dev_err(i2c_dev->dev, "ERROR: Freq {%d/%d}\n",
+ setup->speed_freq, i2c_specs[setup->speed].rate);
+ return -EINVAL;
+ }
+
+ /* Analog and Digital Filters */
+ af_delay_min =
+ (setup->analog_filter ?
+ STM32F7_I2C_ANALOG_FILTER_DELAY_MIN : 0);
+ af_delay_max =
+ (setup->analog_filter ?
+ STM32F7_I2C_ANALOG_FILTER_DELAY_MAX : 0);
+ dnf_delay = setup->dnf * i2cclk;
+
+ sdadel_min = setup->fall_time - i2c_specs[setup->speed].hddat_min -
+ af_delay_min - (setup->dnf + 3) * i2cclk;
+
+ sdadel_max = i2c_specs[setup->speed].vddat_max - setup->rise_time -
+ af_delay_max - (setup->dnf + 4) * i2cclk;
+
+ scldel_min = setup->rise_time + i2c_specs[setup->speed].sudat_min;
+
+ if (sdadel_min < 0)
+ sdadel_min = 0;
+ if (sdadel_max < 0)
+ sdadel_max = 0;
+
+ dev_dbg(i2c_dev->dev, "SDADEL(min/max): %i/%i, SCLDEL(Min): %i\n",
+ sdadel_min, sdadel_max, scldel_min);
+
+ INIT_LIST_HEAD(&solutions);
+ /* Compute possible values for PRESC, SCLDEL and SDADEL */
+ for (p = 0; p < STM32F7_PRESC_MAX; p++) {
+ for (l = 0; l < STM32F7_SCLDEL_MAX; l++) {
+ u32 scldel = (l + 1) * (p + 1) * i2cclk;
+
+ if (scldel < scldel_min)
+ continue;
+
+ for (a = 0; a < STM32F7_SDADEL_MAX; a++) {
+ u32 sdadel = (a * (p + 1) + 1) * i2cclk;
+
+ if (((sdadel >= sdadel_min) &&
+ (sdadel <= sdadel_max)) &&
+ (p != p_prev)) {
+ v = kmalloc(sizeof(*v), GFP_KERNEL);
+ if (!v) {
+ ret = -ENOMEM;
+ goto exit;
+ }
+
+ v->presc = p;
+ v->scldel = l;
+ v->sdadel = a;
+ p_prev = p;
+
+ list_add_tail(&v->node,
+ &solutions);
+ }
+ }
+ }
+ }
+
+ if (list_empty(&solutions)) {
+ dev_err(i2c_dev->dev, "no Prescaler solution\n");
+ ret = -EPERM;
+ goto exit;
+ }
+
+ tsync = af_delay_min + dnf_delay + (2 * i2cclk);
+ s = NULL;
+ clk_max = NSEC_PER_SEC / i2c_specs[setup->speed].rate_min;
+ clk_min = NSEC_PER_SEC / i2c_specs[setup->speed].rate_max;
+
+ /*
+ * Among Prescaler possibilities discovered above figures out SCL Low
+ * and High Period. Provided:
+ * - SCL Low Period has to be higher than Low Period of tehs SCL Clock
+ * defined by I2C Specification. I2C Clock has to be lower than
+ * (SCL Low Period - Analog/Digital filters) / 4.
+ * - SCL High Period has to be lower than High Period of the SCL Clock
+ * defined by I2C Specification
+ * - I2C Clock has to be lower than SCL High Period
+ */
+ list_for_each_entry(v, &solutions, node) {
+ u32 prescaler = (v->presc + 1) * i2cclk;
+
+ for (l = 0; l < STM32F7_SCLL_MAX; l++) {
+ u32 tscl_l = (l + 1) * prescaler + tsync;
+
+ if ((tscl_l < i2c_specs[setup->speed].l_min) ||
+ (i2cclk >=
+ ((tscl_l - af_delay_min - dnf_delay) / 4))) {
+ continue;
+ }
+
+ for (h = 0; h < STM32F7_SCLH_MAX; h++) {
+ u32 tscl_h = (h + 1) * prescaler + tsync;
+ u32 tscl = tscl_l + tscl_h +
+ setup->rise_time + setup->fall_time;
+
+ if ((tscl >= clk_min) && (tscl <= clk_max) &&
+ (tscl_h >= i2c_specs[setup->speed].h_min) &&
+ (i2cclk < tscl_h)) {
+ int clk_error = tscl - i2cbus;
+
+ if (clk_error < 0)
+ clk_error = -clk_error;
+
+ if (clk_error < clk_error_prev) {
+ clk_error_prev = clk_error;
+ v->scll = l;
+ v->sclh = h;
+ s = v;
+ }
+ }
+ }
+ }
+ }
+
+ if (!s) {
+ dev_err(i2c_dev->dev, "no solution at all\n");
+ ret = -EPERM;
+ goto exit;
+ }
+
+ output->presc = s->presc;
+ output->scldel = s->scldel;
+ output->sdadel = s->sdadel;
+ output->scll = s->scll;
+ output->sclh = s->sclh;
+
+ dev_dbg(i2c_dev->dev,
+ "Presc: %i, scldel: %i, sdadel: %i, scll: %i, sclh: %i\n",
+ output->presc,
+ output->scldel, output->sdadel,
+ output->scll, output->sclh);
+
+exit:
+ /* Release list and memory */
+ list_for_each_entry_safe(v, _v, &solutions, node) {
+ list_del(&v->node);
+ kfree(v);
+ }
+
+ return ret;
+}
+
+static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
+ struct stm32f7_i2c_setup *setup)
+{
+ int ret = 0;
+
+ setup->speed = i2c_dev->speed;
+ setup->speed_freq = i2c_specs[setup->speed].rate;
+ setup->clock_src = clk_get_rate(i2c_dev->clk);
+
+ if (!setup->clock_src) {
+ dev_err(i2c_dev->dev, "clock rate is 0\n");
+ return -EINVAL;
+ }
+
+ do {
+ ret = stm32f7_i2c_compute_timing(i2c_dev, setup,
+ &i2c_dev->timing);
+ if (ret) {
+ dev_err(i2c_dev->dev,
+ "failed to compute I2C timings.\n");
+ if (i2c_dev->speed > STM32_I2C_SPEED_STANDARD) {
+ i2c_dev->speed--;
+ setup->speed = i2c_dev->speed;
+ setup->speed_freq =
+ i2c_specs[setup->speed].rate;
+ dev_warn(i2c_dev->dev,
+ "downgrade I2C Speed Freq to (%i)\n",
+ i2c_specs[setup->speed].rate);
+ } else {
+ break;
+ }
+ }
+ } while (ret);
+
+ if (ret) {
+ dev_err(i2c_dev->dev, "Impossible to compute I2C timings.\n");
+ return ret;
+ }
+
+ dev_dbg(i2c_dev->dev, "I2C Speed(%i), Freq(%i), Clk Source(%i)\n",
+ setup->speed, setup->speed_freq, setup->clock_src);
+ dev_dbg(i2c_dev->dev, "I2C Rise(%i) and Fall(%i) Time\n",
+ setup->rise_time, setup->fall_time);
+ dev_dbg(i2c_dev->dev, "I2C Analog Filter(%s), DNF(%i)\n",
+ (setup->analog_filter ? "On" : "Off"), setup->dnf);
+
+ return 0;
+}
+
+static void stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
+{
+ struct stm32f7_i2c_timings *t = &i2c_dev->timing;
+ u32 timing = 0;
+
+ /* Timing settings */
+ timing |= STM32F7_I2C_TIMINGR_PRESC(t->presc);
+ timing |= STM32F7_I2C_TIMINGR_SCLDEL(t->scldel);
+ timing |= STM32F7_I2C_TIMINGR_SDADEL(t->sdadel);
+ timing |= STM32F7_I2C_TIMINGR_SCLH(t->sclh);
+ timing |= STM32F7_I2C_TIMINGR_SCLL(t->scll);
+ writel_relaxed(timing, i2c_dev->base + STM32F7_I2C_TIMINGR);
+
+ /* Enable I2C */
+ if (i2c_dev->setup->analog_filter)
+ stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
+ STM32F7_I2C_CR1_ANFOFF);
+ else
+ stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
+ STM32F7_I2C_CR1_ANFOFF);
+ stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
+ STM32F7_I2C_CR1_PE);
+}
+
+static void stm32f7_i2c_write_tx_data(struct stm32f7_i2c_dev *i2c_dev)
+{
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ void __iomem *base = i2c_dev->base;
+
+ if (f7_msg->count) {
+ writeb_relaxed(*f7_msg->buf++, base + STM32F7_I2C_TXDR);
+ f7_msg->count--;
+ }
+}
+
+static void stm32f7_i2c_read_rx_data(struct stm32f7_i2c_dev *i2c_dev)
+{
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ void __iomem *base = i2c_dev->base;
+
+ if (f7_msg->count) {
+ *f7_msg->buf++ = readb_relaxed(base + STM32F7_I2C_RXDR);
+ f7_msg->count--;
+ }
+}
+
+static void stm32f7_i2c_reload(struct stm32f7_i2c_dev *i2c_dev)
+{
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ u32 cr2;
+
+ cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
+
+ cr2 &= ~STM32F7_I2C_CR2_NBYTES_MASK;
+ if (f7_msg->count > STM32F7_I2C_MAX_LEN) {
+ cr2 |= STM32F7_I2C_CR2_NBYTES(STM32F7_I2C_MAX_LEN);
+ } else {
+ cr2 &= ~STM32F7_I2C_CR2_RELOAD;
+ cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
+ }
+
+ writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
+}
+
+static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
+{
+ u32 status;
+ int ret;
+
+ ret = readl_relaxed_poll_timeout(i2c_dev->base + STM32F7_I2C_ISR,
+ status,
+ !(status & STM32F7_I2C_ISR_BUSY),
+ 10, 1000);
+ if (ret) {
+ dev_dbg(i2c_dev->dev, "bus busy\n");
+ ret = -EBUSY;
+ }
+
+ return ret;
+}
+
+static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
+ struct i2c_msg *msg)
+{
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ void __iomem *base = i2c_dev->base;
+ u32 cr1, cr2;
+
+ f7_msg->addr = msg->addr;
+ f7_msg->buf = msg->buf;
+ f7_msg->count = msg->len;
+ f7_msg->result = 0;
+ f7_msg->stop = (i2c_dev->msg_id >= i2c_dev->msg_num - 1);
+
+ reinit_completion(&i2c_dev->complete);
+
+ cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
+ cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
+
+ /* Set transfer direction */
+ cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+ if (msg->flags & I2C_M_RD)
+ cr2 |= STM32F7_I2C_CR2_RD_WRN;
+
+ /* Set slave address */
+ cr2 &= ~STM32F7_I2C_CR2_SADD7_MASK;
+ cr2 |= STM32F7_I2C_CR2_SADD7(f7_msg->addr);
+
+ /* Set nb bytes to transfer and reload if needed */
+ cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK | STM32F7_I2C_CR2_RELOAD);
+ if (f7_msg->count > STM32F7_I2C_MAX_LEN) {
+ cr2 |= STM32F7_I2C_CR2_NBYTES(STM32F7_I2C_MAX_LEN);
+ cr2 |= STM32F7_I2C_CR2_RELOAD;
+ } else {
+ cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
+ }
+
+ /* Enable NACK, STOP, error and transfer complete interrupts */
+ cr1 |= STM32F7_I2C_CR1_ERRIE | STM32F7_I2C_CR1_TCIE |
+ STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE;
+
+ /* Clear TX/RX interrupt */
+ cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
+
+ /* Enable RX/TX interrupt according to msg direction */
+ if (msg->flags & I2C_M_RD)
+ cr1 |= STM32F7_I2C_CR1_RXIE;
+ else
+ cr1 |= STM32F7_I2C_CR1_TXIE;
+
+ /* Configure Start/Repeated Start */
+ cr2 |= STM32F7_I2C_CR2_START;
+
+ /* Write configurations registers */
+ writel_relaxed(cr1, base + STM32F7_I2C_CR1);
+ writel_relaxed(cr2, base + STM32F7_I2C_CR2);
+}
+
+static void stm32f7_i2c_disable_irq(struct stm32f7_i2c_dev *i2c_dev, u32 mask)
+{
+ stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1, mask);
+}
+
+static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
+{
+ struct stm32f7_i2c_dev *i2c_dev = data;
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ void __iomem *base = i2c_dev->base;
+ u32 status, mask;
+
+ status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
+
+ /* Tx empty */
+ if (status & STM32F7_I2C_ISR_TXIS)
+ stm32f7_i2c_write_tx_data(i2c_dev);
+
+ /* RX not empty */
+ if (status & STM32F7_I2C_ISR_RXNE)
+ stm32f7_i2c_read_rx_data(i2c_dev);
+
+ /* NACK received */
+ if (status & STM32F7_I2C_ISR_NACKF) {
+ dev_dbg(i2c_dev->dev, "<%s>: Receive NACK\n", __func__);
+ writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
+ f7_msg->result = -EBADE;
+ }
+
+ /* STOP detection flag */
+ if (status & STM32F7_I2C_ISR_STOPF) {
+ /* Disable interrupts */
+ stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
+
+ /* Clear STOP flag */
+ writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
+
+ complete(&i2c_dev->complete);
+ }
+
+ /* Transfer complete */
+ if (status & STM32F7_I2C_ISR_TC) {
+ if (f7_msg->stop) {
+ mask = STM32F7_I2C_CR2_STOP;
+ stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
+ } else {
+ i2c_dev->msg_id++;
+ i2c_dev->msg++;
+ stm32f7_i2c_xfer_msg(i2c_dev, i2c_dev->msg);
+ }
+ }
+
+ /*
+ * Transfer Complete Reload: 255 data bytes have been transferred
+ * We have to prepare the I2C controller to transfer the remaining
+ * data.
+ */
+ if (status & STM32F7_I2C_ISR_TCR)
+ stm32f7_i2c_reload(i2c_dev);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
+{
+ struct stm32f7_i2c_dev *i2c_dev = data;
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ void __iomem *base = i2c_dev->base;
+ struct device *dev = i2c_dev->dev;
+ u32 status;
+
+ status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
+
+ /* Bus error */
+ if (status & STM32F7_I2C_ISR_BERR) {
+ dev_err(dev, "<%s>: Bus error\n", __func__);
+ writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
+ f7_msg->result = -EIO;
+ }
+
+ /* Arbitration loss */
+ if (status & STM32F7_I2C_ISR_ARLO) {
+ dev_dbg(dev, "<%s>: Arbitration loss\n", __func__);
+ writel_relaxed(STM32F7_I2C_ICR_ARLOCF, base + STM32F7_I2C_ICR);
+ f7_msg->result = -EAGAIN;
+ }
+
+ stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
+
+ complete(&i2c_dev->complete);
+
+ return IRQ_HANDLED;
+}
+
+static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
+ struct i2c_msg msgs[], int num)
+{
+ struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ unsigned long timeout;
+ int ret;
+
+ i2c_dev->msg = msgs;
+ i2c_dev->msg_num = num;
+ i2c_dev->msg_id = 0;
+
+ ret = clk_enable(i2c_dev->clk);
+ if (ret) {
+ dev_err(i2c_dev->dev, "Failed to enable clock\n");
+ return ret;
+ }
+
+ ret = stm32f7_i2c_wait_free_bus(i2c_dev);
+ if (ret)
+ goto clk_free;
+
+ stm32f7_i2c_xfer_msg(i2c_dev, msgs);
+
+ timeout = wait_for_completion_timeout(&i2c_dev->complete,
+ i2c_dev->adap.timeout);
+ ret = f7_msg->result;
+
+ if (!timeout) {
+ dev_dbg(i2c_dev->dev, "Access to slave 0x%x timed out\n",
+ i2c_dev->msg->addr);
+ ret = -ETIMEDOUT;
+ }
+
+clk_free:
+ clk_disable(i2c_dev->clk);
+
+ return (ret < 0) ? ret : num;
+}
+
+static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm stm32f7_i2c_algo = {
+ .master_xfer = stm32f7_i2c_xfer,
+ .functionality = stm32f7_i2c_func,
+};
+
+static int stm32f7_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct stm32f7_i2c_dev *i2c_dev;
+ const struct stm32f7_i2c_setup *setup;
+ struct resource *res;
+ u32 irq_error, irq_event, clk_rate, rise_time, fall_time;
+ 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(&pdev->dev, "Failed to prepare_enable clock\n");
+ return ret;
+ }
+
+ i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
+ ret = device_property_read_u32(&pdev->dev, "clock-frequency",
+ &clk_rate);
+ if (!ret && clk_rate >= 1000000)
+ i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
+ else if (!ret && clk_rate >= 400000)
+ i2c_dev->speed = STM32_I2C_SPEED_FAST;
+ else if (!ret && clk_rate >= 100000)
+ i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
+
+ 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->dev = &pdev->dev;
+
+ ret = devm_request_irq(&pdev->dev, irq_event, stm32f7_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, stm32f7_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;
+ }
+
+ setup = of_device_get_match_data(&pdev->dev);
+ i2c_dev->setup->rise_time = setup->rise_time;
+ i2c_dev->setup->fall_time = setup->fall_time;
+ i2c_dev->setup->dnf = setup->dnf;
+ i2c_dev->setup->analog_filter = setup->analog_filter;
+
+ ret = device_property_read_u32(i2c_dev->dev, "i2c-scl-rising-time-ns",
+ &rise_time);
+ if (!ret)
+ i2c_dev->setup->rise_time = rise_time;
+
+ ret = device_property_read_u32(i2c_dev->dev, "i2c-scl-falling-time-ns",
+ &fall_time);
+ if (!ret)
+ i2c_dev->setup->fall_time = fall_time;
+
+ ret = stm32f7_i2c_setup_timing(i2c_dev, i2c_dev->setup);
+ if (ret)
+ goto clk_free;
+
+ stm32f7_i2c_hw_config(i2c_dev);
+
+ adap = &i2c_dev->adap;
+ i2c_set_adapdata(adap, i2c_dev);
+ snprintf(adap->name, sizeof(adap->name), "STM32F7 I2C(%pa)",
+ &res->start);
+ adap->owner = THIS_MODULE;
+ adap->timeout = 2 * HZ;
+ adap->retries = 0;
+ adap->algo = &stm32f7_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");
+ goto clk_free;
+ }
+
+ platform_set_drvdata(pdev, i2c_dev);
+
+ clk_disable(i2c_dev->clk);
+
+ dev_info(i2c_dev->dev, "STM32F7 I2C-%d bus adapter\n", adap->nr);
+
+ return 0;
+
+clk_free:
+ clk_disable_unprepare(i2c_dev->clk);
+
+ return ret;
+}
+
+static int stm32f7_i2c_remove(struct platform_device *pdev)
+{
+ struct stm32f7_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 stm32f7_i2c_match[] = {
+ { .compatible = "st,stm32f7-i2c", .data = &stm32f7_setup},
+ {},
+};
+MODULE_DEVICE_TABLE(of, stm32f7_i2c_match);
+
+static struct platform_driver stm32f7_i2c_driver = {
+ .driver = {
+ .name = "stm32f7-i2c",
+ .of_match_table = stm32f7_i2c_match,
+ },
+ .probe = stm32f7_i2c_probe,
+ .remove = stm32f7_i2c_remove,
+};
+
+module_platform_driver(stm32f7_i2c_driver);
+
+MODULE_AUTHOR("M'boumba Cedric Madianga <cedric.madianga@gmail.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32F7 I2C driver");
+MODULE_LICENSE("GPL v2");
--
2.7.4
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