This patch adds initial support for the STM32F7 I2C controller.
It was tested to work with the STM32MP157C.
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
drivers/i2c/busses/Kconfig | 5 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-stm32.c | 863 +++++++++++++++++++++++++++++++++
3 files changed, 869 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-stm32.c
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 2e47cdb491f6..21d2cb21cf5a 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -55,4 +55,9 @@ config I2C_VERSATILE
Say yes if you want to support the I2C serial bus on ARMs Versatile
range of platforms.
+config I2C_STM32
+ bool "STM32 I2C master driver"
+ select RESET_CONTROLLER
+ depends on HAVE_CLK
+
endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 61d7c86e7692..7e450ead2738 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_I2C_OMAP) += i2c-omap.o
obj-$(CONFIG_I2C_TEGRA) += i2c-tegra.o
obj-$(CONFIG_I2C_VERSATILE) += i2c-versatile.o
obj-$(CONFIG_I2C_DESIGNWARE) += i2c-designware.o
+obj-$(CONFIG_I2C_STM32) += i2c-stm32.o
diff --git a/drivers/i2c/busses/i2c-stm32.c b/drivers/i2c/busses/i2c-stm32.c
new file mode 100644
index 000000000000..6af55fb3ffda
--- /dev/null
+++ b/drivers/i2c/busses/i2c-stm32.c
@@ -0,0 +1,863 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2017 STMicroelectronics
+ * Copyright 2019 Ahmad Fatoum, Pengutronix
+ */
+
+#define pr_fmt(fmt) "i2c-stm32: " fmt
+
+#include <common.h>
+#include <i2c/i2c.h>
+#include <init.h>
+#include <linux/clk.h>
+#include <linux/iopoll.h>
+#include <linux/reset.h>
+
+/* STM32 I2C registers */
+struct __packed stm32_i2c_regs {
+ u32 cr1; /* I2C control register 1 */
+ u32 cr2; /* I2C control register 2 */
+ u32 oar1; /* I2C own address 1 register */
+ u32 oar2; /* I2C own address 2 register */
+ u32 timingr; /* I2C timing register */
+ u32 timeoutr; /* I2C timeout register */
+ u32 isr; /* I2C interrupt and status register */
+ u32 icr; /* I2C interrupt clear register */
+ u32 pecr; /* I2C packet error checking register */
+ u32 rxdr; /* I2C receive data register */
+ u32 txdr; /* I2C transmit data register */
+};
+
+#define STM32_I2C_CR1 0x00
+#define STM32_I2C_CR2 0x04
+#define STM32_I2C_TIMINGR 0x10
+#define STM32_I2C_ISR 0x18
+#define STM32_I2C_ICR 0x1C
+#define STM32_I2C_RXDR 0x24
+#define STM32_I2C_TXDR 0x28
+
+/* STM32 I2C control 1 */
+#define STM32_I2C_CR1_ANFOFF BIT(12)
+#define STM32_I2C_CR1_ERRIE BIT(7)
+#define STM32_I2C_CR1_TCIE BIT(6)
+#define STM32_I2C_CR1_STOPIE BIT(5)
+#define STM32_I2C_CR1_NACKIE BIT(4)
+#define STM32_I2C_CR1_ADDRIE BIT(3)
+#define STM32_I2C_CR1_RXIE BIT(2)
+#define STM32_I2C_CR1_TXIE BIT(1)
+#define STM32_I2C_CR1_PE BIT(0)
+
+/* STM32 I2C control 2 */
+#define STM32_I2C_CR2_AUTOEND BIT(25)
+#define STM32_I2C_CR2_RELOAD BIT(24)
+#define STM32_I2C_CR2_NBYTES_MASK GENMASK(23, 16)
+#define STM32_I2C_CR2_NBYTES(n) ((n & 0xff) << 16)
+#define STM32_I2C_CR2_NACK BIT(15)
+#define STM32_I2C_CR2_STOP BIT(14)
+#define STM32_I2C_CR2_START BIT(13)
+#define STM32_I2C_CR2_HEAD10R BIT(12)
+#define STM32_I2C_CR2_ADD10 BIT(11)
+#define STM32_I2C_CR2_RD_WRN BIT(10)
+#define STM32_I2C_CR2_SADD10_MASK GENMASK(9, 0)
+#define STM32_I2C_CR2_SADD10(n) (n & STM32_I2C_CR2_SADD10_MASK)
+#define STM32_I2C_CR2_SADD7_MASK GENMASK(7, 1)
+#define STM32_I2C_CR2_SADD7(n) ((n & 0x7f) << 1)
+#define STM32_I2C_CR2_RESET_MASK (STM32_I2C_CR2_HEAD10R \
+ | STM32_I2C_CR2_NBYTES_MASK \
+ | STM32_I2C_CR2_SADD7_MASK \
+ | STM32_I2C_CR2_RELOAD \
+ | STM32_I2C_CR2_RD_WRN)
+
+/* STM32 I2C Interrupt Status */
+#define STM32_I2C_ISR_BUSY BIT(15)
+#define STM32_I2C_ISR_ARLO BIT(9)
+#define STM32_I2C_ISR_BERR BIT(8)
+#define STM32_I2C_ISR_TCR BIT(7)
+#define STM32_I2C_ISR_TC BIT(6)
+#define STM32_I2C_ISR_STOPF BIT(5)
+#define STM32_I2C_ISR_NACKF BIT(4)
+#define STM32_I2C_ISR_ADDR BIT(3)
+#define STM32_I2C_ISR_RXNE BIT(2)
+#define STM32_I2C_ISR_TXIS BIT(1)
+#define STM32_I2C_ISR_TXE BIT(0)
+#define STM32_I2C_ISR_ERRORS (STM32_I2C_ISR_BERR \
+ | STM32_I2C_ISR_ARLO)
+
+/* STM32 I2C Interrupt Clear */
+#define STM32_I2C_ICR_ARLOCF BIT(9)
+#define STM32_I2C_ICR_BERRCF BIT(8)
+#define STM32_I2C_ICR_STOPCF BIT(5)
+#define STM32_I2C_ICR_NACKCF BIT(4)
+
+/* STM32 I2C Timing */
+#define STM32_I2C_TIMINGR_PRESC(n) ((n & 0xf) << 28)
+#define STM32_I2C_TIMINGR_SCLDEL(n) ((n & 0xf) << 20)
+#define STM32_I2C_TIMINGR_SDADEL(n) ((n & 0xf) << 16)
+#define STM32_I2C_TIMINGR_SCLH(n) ((n & 0xff) << 8)
+#define STM32_I2C_TIMINGR_SCLL(n) (n & 0xff)
+
+#define STM32_I2C_MAX_LEN 0xff
+
+#define STM32_I2C_DNF_DEFAULT 0
+#define STM32_I2C_DNF_MAX 16
+
+#define STM32_I2C_ANALOG_FILTER_ENABLE 1
+#define STM32_I2C_ANALOG_FILTER_DELAY_MIN 50 /* ns */
+#define STM32_I2C_ANALOG_FILTER_DELAY_MAX 260 /* ns */
+
+#define STM32_I2C_RISE_TIME_DEFAULT 25 /* ns */
+#define STM32_I2C_FALL_TIME_DEFAULT 10 /* ns */
+
+#define STM32_PRESC_MAX BIT(4)
+#define STM32_SCLDEL_MAX BIT(4)
+#define STM32_SDADEL_MAX BIT(4)
+#define STM32_SCLH_MAX BIT(8)
+#define STM32_SCLL_MAX BIT(8)
+
+#define STANDARD_RATE 100000
+#define FAST_RATE 400000
+#define FAST_PLUS_RATE 1000000
+
+enum stm32_i2c_speed {
+ STM32_I2C_SPEED_STANDARD, /* 100 kHz */
+ STM32_I2C_SPEED_FAST, /* 400 kHz */
+ STM32_I2C_SPEED_FAST_PLUS, /* 1 MHz */
+ STM32_I2C_SPEED_END,
+};
+
+/**
+ * struct stm32_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 stm32_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 stm32_i2c_setup - private I2C timing setup parameters
+ * @speed: I2C speed mode (standard, Fast Plus)
+ * @speed_freq: actual I2C speed frequency (Hz)
+ * @clock_src: I2C clock source frequency (Hz)
+ * @dnf: Digital filter coefficient (0-16)
+ * @analog_filter: Analog filter delay (On/Off)
+ * @timings: I2C timings parameters
+ */
+struct stm32_i2c_setup {
+ enum stm32_i2c_speed speed;
+ u32 speed_freq;
+ u32 clock_src;
+ u8 dnf;
+ bool analog_filter;
+ struct i2c_timings timings;
+};
+
+/**
+ * struct stm32_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 stm32_i2c_timings {
+ struct list_head node;
+ u8 presc;
+ u8 scldel;
+ u8 sdadel;
+ u8 sclh;
+ u8 scll;
+};
+
+static const struct stm32_i2c_spec i2c_specs[] = {
+ [STM32_I2C_SPEED_STANDARD] = {
+ .rate = STANDARD_RATE,
+ .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 = FAST_RATE,
+ .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 = FAST_PLUS_RATE,
+ .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 stm32_i2c {
+ struct stm32_i2c_regs __iomem *regs;
+ struct clk *clk;
+ struct i2c_adapter adapter;
+ struct stm32_i2c_setup setup;
+};
+#define to_stm32_i2c(a) container_of(a, struct stm32_i2c, adapter)
+
+static inline int stm32_i2c_check_device_busy(struct stm32_i2c *priv)
+{
+ u32 status = readl(&priv->regs->isr);
+ return status & STM32_I2C_ISR_BUSY;
+}
+
+static void stm32_i2c_message_start(struct stm32_i2c *i2c_priv,
+ struct i2c_msg *msg, bool stop)
+{
+ struct stm32_i2c_regs *regs = i2c_priv->regs;
+ u32 cr2 = readl(®s->cr2);
+
+ /* Set transfer direction */
+ cr2 &= ~STM32_I2C_CR2_RD_WRN;
+ if (msg->flags & I2C_M_RD)
+ cr2 |= STM32_I2C_CR2_RD_WRN;
+
+ /* Set slave address */
+ cr2 &= ~(STM32_I2C_CR2_HEAD10R | STM32_I2C_CR2_ADD10);
+ if (msg->flags & I2C_M_TEN) {
+ cr2 &= ~STM32_I2C_CR2_SADD10_MASK;
+ cr2 |= STM32_I2C_CR2_SADD10(msg->addr);
+ cr2 |= STM32_I2C_CR2_ADD10;
+ } else {
+ cr2 &= ~STM32_I2C_CR2_SADD7_MASK;
+ cr2 |= STM32_I2C_CR2_SADD7(msg->addr);
+ }
+
+ /* Set nb bytes to transfer and reload or autoend bits */
+ cr2 &= ~(STM32_I2C_CR2_NBYTES_MASK | STM32_I2C_CR2_RELOAD |
+ STM32_I2C_CR2_AUTOEND);
+ if (msg->len > STM32_I2C_MAX_LEN) {
+ cr2 |= STM32_I2C_CR2_NBYTES(STM32_I2C_MAX_LEN);
+ cr2 |= STM32_I2C_CR2_RELOAD;
+ } else {
+ cr2 |= STM32_I2C_CR2_NBYTES(msg->len);
+ }
+
+ /* Write configurations register */
+ writel(cr2, ®s->cr2);
+
+ /* START/ReSTART generation */
+ setbits_le32(®s->cr2, STM32_I2C_CR2_START);
+}
+
+/*
+ * RELOAD mode must be selected if total number of data bytes to be
+ * sent is greater than MAX_LEN
+ */
+
+static void stm32_i2c_handle_reload(struct stm32_i2c *i2c_priv,
+ struct i2c_msg *msg, bool stop)
+{
+ struct stm32_i2c_regs *regs = i2c_priv->regs;
+ u32 cr2 = readl(®s->cr2);
+
+ cr2 &= ~STM32_I2C_CR2_NBYTES_MASK;
+
+ if (msg->len > STM32_I2C_MAX_LEN) {
+ cr2 |= STM32_I2C_CR2_NBYTES(STM32_I2C_MAX_LEN);
+ } else {
+ cr2 &= ~STM32_I2C_CR2_RELOAD;
+ cr2 |= STM32_I2C_CR2_NBYTES(msg->len);
+ }
+
+ writel(cr2, ®s->cr2);
+}
+
+static int stm32_i2c_wait_flags(struct stm32_i2c *i2c_priv,
+ u32 flags, u32 *status)
+{
+ struct stm32_i2c_regs *regs = i2c_priv->regs;
+
+ return readl_poll_timeout(®s->isr, *status,
+ *status & flags, USEC_PER_SEC);
+}
+
+static int stm32_i2c_check_end_of_message(struct stm32_i2c *i2c_priv)
+{
+ struct stm32_i2c_regs *regs = i2c_priv->regs;
+ u32 mask = STM32_I2C_ISR_ERRORS | STM32_I2C_ISR_NACKF |
+ STM32_I2C_ISR_STOPF;
+ struct device_d *dev = &i2c_priv->adapter.dev;
+ u32 status;
+ int ret;
+
+ ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
+ if (ret)
+ return ret;
+
+ if (status & STM32_I2C_ISR_BERR) {
+ dev_dbg(dev, "Bus error\n");
+
+ /* Clear BERR flag */
+ setbits_le32(®s->icr, STM32_I2C_ICR_BERRCF);
+
+ return -EIO;
+ }
+
+ if (status & STM32_I2C_ISR_ARLO) {
+ dev_dbg(dev, "Arbitration lost\n");
+
+ /* Clear ARLO flag */
+ setbits_le32(®s->icr, STM32_I2C_ICR_ARLOCF);
+
+ return -EAGAIN;
+ }
+
+ if (status & STM32_I2C_ISR_NACKF) {
+ dev_dbg(dev, "Receive NACK\n");
+
+ /* Clear NACK flag */
+ setbits_le32(®s->icr, STM32_I2C_ICR_NACKCF);
+
+ /* Wait until STOPF flag is set */
+ mask = STM32_I2C_ISR_STOPF;
+ ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
+ if (ret)
+ return ret;
+
+ ret = -EIO;
+ }
+
+ if (status & STM32_I2C_ISR_STOPF) {
+ /* Clear STOP flag */
+ setbits_le32(®s->icr, STM32_I2C_ICR_STOPCF);
+
+ /* Clear control register 2 */
+ setbits_le32(®s->cr2, STM32_I2C_CR2_RESET_MASK);
+ }
+
+ return ret;
+}
+
+static int stm32_i2c_message_xfer(struct stm32_i2c *i2c_priv,
+ struct i2c_msg *msg, bool stop)
+{
+ struct stm32_i2c_regs *regs = i2c_priv->regs;
+ int len = msg->len;
+ u8 *buf = msg->buf;
+ u32 status;
+ u32 mask = msg->flags & I2C_M_RD ? STM32_I2C_ISR_RXNE :
+ STM32_I2C_ISR_TXIS | STM32_I2C_ISR_NACKF;
+ int bytes_to_rw = min(len, STM32_I2C_MAX_LEN);
+ int ret = 0;
+
+ /* Add errors */
+ mask |= STM32_I2C_ISR_ERRORS;
+
+ stm32_i2c_message_start(i2c_priv, msg, stop);
+
+ while (len) {
+ /*
+ * Wait until TXIS/NACKF/BERR/ARLO flags or
+ * RXNE/BERR/ARLO flags are set
+ */
+ ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
+ if (ret)
+ break;
+
+ if (status & (STM32_I2C_ISR_NACKF | STM32_I2C_ISR_ERRORS))
+ break;
+
+ if (status & STM32_I2C_ISR_RXNE) {
+ *buf++ = readb(®s->rxdr);
+ len--;
+ bytes_to_rw--;
+ }
+
+ if (status & STM32_I2C_ISR_TXIS) {
+ writeb(*buf++, ®s->txdr);
+ len--;
+ bytes_to_rw--;
+ }
+
+ if (!bytes_to_rw && len) {
+ /* Wait until TCR flag is set */
+ mask = STM32_I2C_ISR_TCR;
+ ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
+ if (ret)
+ break;
+
+ bytes_to_rw = min(len, STM32_I2C_MAX_LEN);
+ mask = msg->flags & I2C_M_RD ? STM32_I2C_ISR_RXNE :
+ STM32_I2C_ISR_TXIS | STM32_I2C_ISR_NACKF;
+
+ stm32_i2c_handle_reload(i2c_priv, msg, stop);
+ } else if (!bytes_to_rw) {
+ /* Wait until TC flag is set */
+ mask = STM32_I2C_ISR_TC;
+ ret = stm32_i2c_wait_flags(i2c_priv, mask, &status);
+ if (ret)
+ break;
+
+ if (!stop)
+ /* Message sent, new message has to be sent */
+ return 0;
+ }
+ }
+
+ /* End of transfer, send stop condition */
+ mask = STM32_I2C_CR2_STOP;
+ setbits_le32(®s->cr2, mask);
+
+ return stm32_i2c_check_end_of_message(i2c_priv);
+}
+
+static int stm32_i2c_xfer(struct i2c_adapter *adapter,
+ struct i2c_msg *msg, int nmsgs)
+{
+ struct stm32_i2c *i2c_priv = to_stm32_i2c(adapter);
+ int ret;
+ int i;
+
+ ret = stm32_i2c_check_device_busy(i2c_priv);
+ if (ret)
+ return -EBUSY;
+
+ for (i = 0; i < nmsgs; i++) {
+ ret = stm32_i2c_message_xfer(i2c_priv, &msg[i], i == nmsgs - 1);
+ if (ret)
+ return ret;
+ }
+
+ return nmsgs;
+}
+
+
+static int stm32_i2c_compute_solutions(struct stm32_i2c_setup *setup,
+ struct list_head *solutions)
+{
+ struct stm32_i2c_timings *v;
+ u32 p_prev = STM32_PRESC_MAX;
+ u32 i2cclk = DIV_ROUND_CLOSEST(NSEC_PER_SEC, setup->clock_src);
+ u32 af_delay_min = 0, af_delay_max = 0;
+ u16 p, l, a;
+ int sdadel_min, sdadel_max, scldel_min;
+ int ret = 0;
+
+ if (setup->analog_filter) {
+ af_delay_min = STM32_I2C_ANALOG_FILTER_DELAY_MIN;
+ af_delay_max = STM32_I2C_ANALOG_FILTER_DELAY_MAX;
+ }
+
+ sdadel_min = i2c_specs[setup->speed].hddat_min + setup->timings.scl_fall_ns -
+ af_delay_min - (setup->dnf + 3) * i2cclk;
+
+ sdadel_max = i2c_specs[setup->speed].vddat_max - setup->timings.scl_rise_ns -
+ af_delay_max - (setup->dnf + 4) * i2cclk;
+
+ scldel_min = setup->timings.scl_rise_ns + i2c_specs[setup->speed].sudat_min;
+
+ if (sdadel_min < 0)
+ sdadel_min = 0;
+ if (sdadel_max < 0)
+ sdadel_max = 0;
+
+ pr_debug("SDADEL(min/max): %i/%i, SCLDEL(Min): %i\n",
+ sdadel_min, sdadel_max, scldel_min);
+
+ /* Compute possible values for PRESC, SCLDEL and SDADEL */
+ for (p = 0; p < STM32_PRESC_MAX; p++) {
+ for (l = 0; l < STM32_SCLDEL_MAX; l++) {
+ u32 scldel = (l + 1) * (p + 1) * i2cclk;
+
+ if (scldel < scldel_min)
+ continue;
+
+ for (a = 0; a < STM32_SDADEL_MAX; a++) {
+ u32 sdadel = (a * (p + 1) + 1) * i2cclk;
+
+ if (((sdadel >= sdadel_min) &&
+ (sdadel <= sdadel_max)) &&
+ (p != p_prev)) {
+ v = calloc(1, sizeof(*v));
+ if (!v)
+ return -ENOMEM;
+
+ v->presc = p;
+ v->scldel = l;
+ v->sdadel = a;
+ p_prev = p;
+
+ list_add_tail(&v->node, solutions);
+ break;
+ }
+ }
+
+ if (p_prev == p)
+ break;
+ }
+ }
+
+ if (list_empty(solutions))
+ ret = -EPERM;
+
+ return ret;
+}
+
+static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
+ struct list_head *solutions,
+ struct stm32_i2c_timings *s)
+{
+ struct stm32_i2c_timings *v;
+ u32 i2cbus = DIV_ROUND_CLOSEST(NSEC_PER_SEC, setup->speed_freq);
+ u32 clk_error_prev = i2cbus;
+ u32 i2cclk = DIV_ROUND_CLOSEST(NSEC_PER_SEC, setup->clock_src);
+ u32 clk_min, clk_max;
+ u32 af_delay_min = 0;
+ u32 dnf_delay;
+ u32 tsync;
+ u16 l, h;
+ bool sol_found = false;
+ int ret = 0;
+
+ if (setup->analog_filter)
+ af_delay_min = STM32_I2C_ANALOG_FILTER_DELAY_MIN;
+
+ dnf_delay = setup->dnf * i2cclk;
+
+ tsync = af_delay_min + dnf_delay + (2 * i2cclk);
+ 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 the 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 < STM32_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 < STM32_SCLH_MAX; h++) {
+ u32 tscl_h = (h + 1) * prescaler + tsync;
+ u32 tscl = tscl_l + tscl_h +
+ setup->timings.scl_rise_ns +
+ setup->timings.scl_fall_ns;
+
+ 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;
+ sol_found = true;
+ memcpy(s, v, sizeof(*s));
+ }
+ }
+ }
+ }
+ }
+
+ if (!sol_found)
+ ret = -EPERM;
+
+ return ret;
+}
+
+static int stm32_i2c_compute_timing(struct stm32_i2c *i2c_priv,
+ struct stm32_i2c_setup *setup,
+ struct stm32_i2c_timings *output)
+{
+ struct device_d *dev = &i2c_priv->adapter.dev;
+ struct stm32_i2c_timings *v, *_v;
+ struct list_head solutions;
+ int ret;
+
+ if (setup->speed >= STM32_I2C_SPEED_END) {
+ dev_err(dev, "speed out of bound {%d/%d}\n",
+ setup->speed, STM32_I2C_SPEED_END - 1);
+ return -EINVAL;
+ }
+
+ if ((setup->timings.scl_rise_ns > i2c_specs[setup->speed].rise_max) ||
+ (setup->timings.scl_fall_ns > i2c_specs[setup->speed].fall_max)) {
+ dev_err(dev, "timings out of bound Rise{%d>%d}/Fall{%d>%d}\n",
+ setup->timings.scl_rise_ns, i2c_specs[setup->speed].rise_max,
+ setup->timings.scl_fall_ns, i2c_specs[setup->speed].fall_max);
+ return -EINVAL;
+ }
+
+ if (setup->dnf > STM32_I2C_DNF_MAX) {
+ dev_err(dev, "DNF out of bound %d/%d\n",
+ setup->dnf, STM32_I2C_DNF_MAX);
+ return -EINVAL;
+ }
+
+ if (setup->speed_freq > i2c_specs[setup->speed].rate) {
+ dev_err(dev, "Freq {%d/%d}\n",
+ setup->speed_freq, i2c_specs[setup->speed].rate);
+ return -EINVAL;
+ }
+
+ INIT_LIST_HEAD(&solutions);
+ ret = stm32_i2c_compute_solutions(setup, &solutions);
+ if (ret) {
+ if (ret == -EPERM)
+ dev_err(dev, "No prescaler solution\n");
+ goto exit;
+ }
+
+ ret = stm32_i2c_choose_solution(setup, &solutions, output);
+ if (ret) {
+ if (ret == -EPERM)
+ dev_err(dev, "no solution at all\n");
+ goto exit;
+ }
+
+ dev_dbg(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);
+ free(v);
+ }
+
+ return ret;
+}
+
+static int stm32_i2c_setup_timing(struct stm32_i2c *i2c_priv,
+ enum stm32_i2c_speed speed,
+ struct stm32_i2c_timings *timing)
+{
+ struct device_d *dev = &i2c_priv->adapter.dev;
+ struct stm32_i2c_setup *setup = &i2c_priv->setup;
+ int ret = 0;
+
+ setup->speed = speed;
+ setup->speed_freq = i2c_specs[setup->speed].rate;
+ setup->clock_src = clk_get_rate(i2c_priv->clk);
+
+ if (!setup->clock_src) {
+ dev_err(dev, "clock rate is 0\n");
+ return -EINVAL;
+ }
+
+ do {
+ ret = stm32_i2c_compute_timing(i2c_priv, setup, timing);
+ if (ret) {
+ dev_dbg(dev, "failed to compute I2C timings.\n");
+ if (speed > STM32_I2C_SPEED_STANDARD) {
+ speed--;
+ setup->speed = speed;
+ setup->speed_freq = i2c_specs[setup->speed].rate;
+ dev_dbg(dev, "downgrade I2C Speed Freq to (%i)\n",
+ i2c_specs[setup->speed].rate);
+ } else {
+ break;
+ }
+ }
+ } while (ret);
+
+ if (ret) {
+ dev_err(dev, "impossible to compute I2C timings.\n");
+ return ret;
+ }
+
+ dev_dbg(dev, "I2C Speed(%i), Freq(%i), Clk Source(%i)\n",
+ setup->speed, setup->speed_freq, setup->clock_src);
+ dev_dbg(dev, "I2C Rise(%i) and Fall(%i) Time\n",
+ setup->timings.scl_rise_ns, setup->timings.scl_fall_ns);
+ dev_dbg(dev, "I2C Analog Filter(%s), DNF(%i)\n",
+ setup->analog_filter ? "On" : "Off", setup->dnf);
+
+ return 0;
+}
+
+static int stm32_i2c_hw_config(struct stm32_i2c *i2c_priv,
+ enum stm32_i2c_speed speed)
+{
+ struct stm32_i2c_regs *regs = i2c_priv->regs;
+ struct stm32_i2c_timings t;
+ int ret;
+ u32 timing = 0;
+
+ ret = stm32_i2c_setup_timing(i2c_priv, speed, &t);
+ if (ret)
+ return ret;
+
+ /* Disable I2C */
+ clrbits_le32(®s->cr1, STM32_I2C_CR1_PE);
+
+ /* Timing settings */
+ timing |= STM32_I2C_TIMINGR_PRESC(t.presc);
+ timing |= STM32_I2C_TIMINGR_SCLDEL(t.scldel);
+ timing |= STM32_I2C_TIMINGR_SDADEL(t.sdadel);
+ timing |= STM32_I2C_TIMINGR_SCLH(t.sclh);
+ timing |= STM32_I2C_TIMINGR_SCLL(t.scll);
+ writel(timing, ®s->timingr);
+
+ /* Enable I2C */
+ if (i2c_priv->setup.analog_filter)
+ clrbits_le32(®s->cr1, STM32_I2C_CR1_ANFOFF);
+ else
+ setbits_le32(®s->cr1, STM32_I2C_CR1_ANFOFF);
+ setbits_le32(®s->cr1, STM32_I2C_CR1_PE);
+
+ return 0;
+}
+
+static int stm32_i2c_set_bus_speed(struct stm32_i2c *i2c_priv, unsigned speed)
+{
+ struct device_d *parent_dev = i2c_priv->adapter.dev.parent;
+ enum stm32_i2c_speed stm32_speed;
+ switch (speed) {
+ case STANDARD_RATE:
+ stm32_speed = STM32_I2C_SPEED_STANDARD;
+ break;
+ case FAST_RATE:
+ stm32_speed = STM32_I2C_SPEED_FAST;
+ break;
+ case FAST_PLUS_RATE:
+ stm32_speed = STM32_I2C_SPEED_FAST_PLUS;
+ break;
+ default:
+ dev_warn(parent_dev, "Speed %d not supported\n", speed);
+ return -EINVAL;
+ }
+
+ return stm32_i2c_hw_config(i2c_priv, stm32_speed);
+}
+
+static int __init stm32_i2c_probe(struct device_d *dev)
+{
+ struct resource *iores;
+ struct stm32_i2c *stm32_i2c;
+ struct i2c_platform_data *pdata;
+ struct reset_control *rst;
+ const struct stm32_i2c_setup *setup;
+ struct i2c_timings *timings;
+ int ret;
+
+ pdata = dev->platform_data;
+
+ stm32_i2c = xzalloc(sizeof(*stm32_i2c));
+
+ stm32_i2c->clk = clk_get(dev, NULL);
+ if (IS_ERR(stm32_i2c->clk))
+ return PTR_ERR(stm32_i2c->clk);
+ clk_enable(stm32_i2c->clk);
+
+ rst = reset_control_get(dev, NULL);
+ if (IS_ERR(rst))
+ return PTR_ERR(rst);
+
+ reset_control_assert(rst);
+ udelay(2);
+ reset_control_deassert(rst);
+
+ ret = dev_get_drvdata(dev, (const void **)&setup);
+ if (ret)
+ return ret;
+
+ stm32_i2c->setup = *setup;
+ timings = &stm32_i2c->setup.timings;
+
+ /* We've our own defaults, so don't use the i2c_parse_fw_timings ones */
+ i2c_parse_fw_timings(dev, timings, false);
+
+ if (!timings->bus_freq_hz)
+ timings->bus_freq_hz = STANDARD_RATE;
+ if (!timings->scl_rise_ns)
+ timings->scl_rise_ns = STM32_I2C_RISE_TIME_DEFAULT;
+ if (!timings->scl_fall_ns)
+ timings->scl_fall_ns = STM32_I2C_FALL_TIME_DEFAULT;
+
+ /* Setup stm32_i2c driver structure */
+ stm32_i2c->adapter.master_xfer = stm32_i2c_xfer;
+ stm32_i2c->adapter.nr = dev->id;
+ stm32_i2c->adapter.dev.parent = dev;
+ stm32_i2c->adapter.dev.device_node = dev->device_node;
+ iores = dev_request_mem_resource(dev, 0);
+ if (IS_ERR(iores))
+ return PTR_ERR(iores);
+
+ stm32_i2c->regs = IOMEM(iores->start);
+
+ if (pdata && pdata->bitrate)
+ timings->bus_freq_hz = pdata->bitrate;
+
+ ret = stm32_i2c_set_bus_speed(stm32_i2c, timings->bus_freq_hz);
+ if (ret)
+ return ret;
+
+ return i2c_add_numbered_adapter(&stm32_i2c->adapter);
+}
+
+static const struct stm32_i2c_setup stm32f7_setup = {
+ .dnf = STM32_I2C_DNF_DEFAULT,
+ .analog_filter = STM32_I2C_ANALOG_FILTER_ENABLE,
+};
+
+static __maybe_unused struct of_device_id stm32_i2c_dt_ids[] = {
+ { .compatible = "st,stm32f7-i2c", .data = &stm32f7_setup, },
+ { /* sentinel */ }
+};
+
+static struct driver_d stm32_i2c_driver = {
+ .probe = stm32_i2c_probe,
+ .name = "stm32f7-i2c",
+ .of_compatible = DRV_OF_COMPAT(stm32_i2c_dt_ids),
+};
+coredevice_platform_driver(stm32_i2c_driver);
--
2.23.0
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