[PATCH v6 1/4] i2c: busses: i2c-st: Add ST I2C controller
Maxime COQUELIN
maxime.coquelin at st.com
Wed Nov 6 03:25:12 EST 2013
This patch adds support to SSC (Synchronous Serial Controller)
I2C driver. This IP also supports SPI protocol, but this is not
the aim of this driver.
This IP is embedded in all ST SoCs for Set-top box platorms, and
supports I2C Standard and Fast modes.
Signed-off-by: Maxime Coquelin <maxime.coquelin at st.com>
---
Documentation/devicetree/bindings/i2c/i2c-st.txt | 41 +
drivers/i2c/busses/Kconfig | 10 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-st.c | 872 ++++++++++++++++++++++
4 files changed, 924 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-st.txt
create mode 100644 drivers/i2c/busses/i2c-st.c
diff --git a/Documentation/devicetree/bindings/i2c/i2c-st.txt b/Documentation/devicetree/bindings/i2c/i2c-st.txt
new file mode 100644
index 0000000..437e0db
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-st.txt
@@ -0,0 +1,41 @@
+ST SSC binding, for I2C mode operation
+
+Required properties :
+- compatible : Must be "st,comms-ssc-i2c" or "st,comms-ssc4-i2c"
+- reg : Offset and length of the register set for the device
+- interrupts : the interrupt specifier
+- clock-names: Must contain "ssc".
+- clocks: Must contain an entry for each name in clock-names. See the common
+ clock bindings.
+- A pinctrl state named "default" must be defined to set pins in mode of
+ operation for I2C transfer.
+
+Optional properties :
+- clock-frequency : Desired I2C bus clock frequency in Hz. If not specified,
+ the default 100 kHz frequency will be used. As only Normal and Fast modes
+ are supported, possible values are 100000 and 400000.
+- st,i2c-min-scl-pulse-width-us : The minimum valid SCL pulse width that is
+ allowed through the deglitch circuit. In units of us.
+- st,i2c-min-sda-pulse-width-us : The minimum valid SDA pulse width that is
+ allowed through the deglitch circuit. In units of us.
+- A pinctrl state named "idle" could be defined to set pins in idle state
+ when I2C instance is not performing a transfer.
+- A pinctrl state named "sleep" could be defined to set pins in sleep state
+ when driver enters in suspend.
+
+
+
+Example :
+
+i2c0: i2c at fed40000 {
+ compatible = "st,comms-ssc4-i2c";
+ reg = <0xfed40000 0x110>;
+ interrupts = <GIC_SPI 187 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&CLK_S_ICN_REG_0>;
+ clock-names = "ssc";
+ clock-frequency = <400000>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_i2c0_default>;
+ st,i2c-min-scl-pulse-width-us = <0>;
+ st,i2c-min-sda-pulse-width-us = <5>;
+};
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index cdcbd83..67f85f9 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -695,6 +695,16 @@ config I2C_SIRF
This driver can also be built as a module. If so, the module
will be called i2c-sirf.
+config I2C_ST
+ tristate "STMicroelectronics SSC I2C support"
+ depends on ARCH_STI
+ help
+ Enable this option to add support for STMicroelectronics SoCs
+ hardware SSC (Synchronous Serial Controller) as an I2C controller.
+
+ This driver can also be built as module. If so, the module
+ will be called i2c-st.
+
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 d00997f..a0f52e4 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_I2C_SH7760) += i2c-sh7760.o
obj-$(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_STU300) += i2c-stu300.o
obj-$(CONFIG_I2C_TEGRA) += i2c-tegra.o
obj-$(CONFIG_I2C_VERSATILE) += i2c-versatile.o
diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c
new file mode 100644
index 0000000..fa57c5e
--- /dev/null
+++ b/drivers/i2c/busses/i2c-st.c
@@ -0,0 +1,872 @@
+/*
+ * Copyright (C) 2013 STMicroelectronics
+ *
+ * I2C master mode controller driver, used in STMicroelectronics devices.
+ *
+ * Author: Maxime Coquelin <maxime.coquelin at st.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+/* SSC registers */
+#define SSC_BRG 0x000
+#define SSC_TBUF 0x004
+#define SSC_RBUF 0x008
+#define SSC_CTL 0x00C
+#define SSC_IEN 0x010
+#define SSC_STA 0x014
+#define SSC_I2C 0x018
+#define SSC_SLAD 0x01C
+#define SSC_REP_START_HOLD 0x020
+#define SSC_START_HOLD 0x024
+#define SSC_REP_START_SETUP 0x028
+#define SSC_DATA_SETUP 0x02C
+#define SSC_STOP_SETUP 0x030
+#define SSC_BUS_FREE 0x034
+#define SSC_TX_FSTAT 0x038
+#define SSC_RX_FSTAT 0x03C
+#define SSC_PRE_SCALER_BRG 0x040
+#define SSC_CLR 0x080
+#define SSC_NOISE_SUPP_WIDTH 0x100
+#define SSC_PRSCALER 0x104
+#define SSC_NOISE_SUPP_WIDTH_DATAOUT 0x108
+#define SSC_PRSCALER_DATAOUT 0x10c
+
+/* SSC Control */
+#define SSC_CTL_DATA_WIDTH_9 0x8
+#define SSC_CTL_DATA_WIDTH_MSK 0xf
+#define SSC_CTL_BM 0xf
+#define SSC_CTL_HB BIT(4)
+#define SSC_CTL_PH BIT(5)
+#define SSC_CTL_PO BIT(6)
+#define SSC_CTL_SR BIT(7)
+#define SSC_CTL_MS BIT(8)
+#define SSC_CTL_EN BIT(9)
+#define SSC_CTL_LPB BIT(10)
+#define SSC_CTL_EN_TX_FIFO BIT(11)
+#define SSC_CTL_EN_RX_FIFO BIT(12)
+#define SSC_CTL_EN_CLST_RX BIT(13)
+
+/* SSC Interrupt Enable */
+#define SSC_IEN_RIEN BIT(0)
+#define SSC_IEN_TIEN BIT(1)
+#define SSC_IEN_TEEN BIT(2)
+#define SSC_IEN_REEN BIT(3)
+#define SSC_IEN_PEEN BIT(4)
+#define SSC_IEN_AASEN BIT(6)
+#define SSC_IEN_STOPEN BIT(7)
+#define SSC_IEN_ARBLEN BIT(8)
+#define SSC_IEN_NACKEN BIT(10)
+#define SSC_IEN_REPSTRTEN BIT(11)
+#define SSC_IEN_TX_FIFO_HALF BIT(12)
+#define SSC_IEN_RX_FIFO_HALF_FULL BIT(14)
+
+/* SSC Status */
+#define SSC_STA_RIR BIT(0)
+#define SSC_STA_TIR BIT(1)
+#define SSC_STA_TE BIT(2)
+#define SSC_STA_RE BIT(3)
+#define SSC_STA_PE BIT(4)
+#define SSC_STA_CLST BIT(5)
+#define SSC_STA_AAS BIT(6)
+#define SSC_STA_STOP BIT(7)
+#define SSC_STA_ARBL BIT(8)
+#define SSC_STA_BUSY BIT(9)
+#define SSC_STA_NACK BIT(10)
+#define SSC_STA_REPSTRT BIT(11)
+#define SSC_STA_TX_FIFO_HALF BIT(12)
+#define SSC_STA_TX_FIFO_FULL BIT(13)
+#define SSC_STA_RX_FIFO_HALF BIT(14)
+
+/* SSC I2C Control */
+#define SSC_I2C_I2CM BIT(0)
+#define SSC_I2C_STRTG BIT(1)
+#define SSC_I2C_STOPG BIT(2)
+#define SSC_I2C_ACKG BIT(3)
+#define SSC_I2C_AD10 BIT(4)
+#define SSC_I2C_TXENB BIT(5)
+#define SSC_I2C_REPSTRTG BIT(11)
+#define SSC_I2C_SLAVE_DISABLE BIT(12)
+
+/* SSC Tx FIFO Status */
+#define SSC_TX_FSTAT_STATUS 0x07
+
+/* SSC Rx FIFO Status */
+#define SSC_RX_FSTAT_STATUS 0x07
+
+/* SSC Clear bit operation */
+#define SSC_CLR_SSCAAS BIT(6)
+#define SSC_CLR_SSCSTOP BIT(7)
+#define SSC_CLR_SSCARBL BIT(8)
+#define SSC_CLR_NACK BIT(10)
+#define SSC_CLR_REPSTRT BIT(11)
+
+/* SSC Clock Prescaler */
+#define SSC_PRSC_VALUE 0x0f
+
+
+#define SSC_TXFIFO_SIZE 0x8
+#define SSC_RXFIFO_SIZE 0x8
+
+enum st_i2c_mode {
+ I2C_MODE_STANDARD,
+ I2C_MODE_FAST,
+ I2C_MODE_END,
+};
+
+/**
+ * struct st_i2c_timings - per-Mode tuning parameters
+ * @rate: I2C bus rate
+ * @rep_start_hold: I2C repeated start hold time requirement
+ * @rep_start_setup: I2C repeated start set up time requirement
+ * @start_hold: I2C start hold time requirement
+ * @data_setup_time: I2C data set up time requirement
+ * @stop_setup_time: I2C stop set up time requirement
+ * @bus_free_time: I2C bus free time requirement
+ * @sda_pulse_min_limit: I2C SDA pulse mini width limit
+ */
+struct st_i2c_timings {
+ u32 rate;
+ u32 rep_start_hold;
+ u32 rep_start_setup;
+ u32 start_hold;
+ u32 data_setup_time;
+ u32 stop_setup_time;
+ u32 bus_free_time;
+ u32 sda_pulse_min_limit;
+};
+
+/**
+ * struct st_i2c_client - client specific data
+ * @addr: 8-bit slave addr, including r/w bit
+ * @count: number of bytes to be transfered
+ * @xfered: number of bytes already transferred
+ * @buf: data buffer
+ * @result: result of the transfer
+ * @stop: last I2C msg to be sent, i.e. STOP to be generated
+ */
+struct st_i2c_client {
+ u8 addr;
+ u32 count;
+ u32 xfered;
+ u8 *buf;
+ int result;
+ bool stop;
+};
+
+/**
+ * struct st_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: interrupt line for th controller
+ * @clk: hw ssc block clock
+ * @mode: I2C mode of the controller. Standard or Fast only supported
+ * @scl_min_width_us: SCL line minimum pulse width in us
+ * @sda_min_width_us: SDA line minimum pulse width in us
+ * @client: I2C transfert information
+ * @busy: I2C transfer on-going
+ */
+struct st_i2c_dev {
+ struct i2c_adapter adap;
+ struct device *dev;
+ void __iomem *base;
+ struct completion complete;
+ int irq;
+ struct clk *clk;
+ int mode;
+ u32 scl_min_width_us;
+ u32 sda_min_width_us;
+ struct st_i2c_client client;
+ bool busy;
+};
+
+static inline void st_i2c_set_bits(void __iomem *reg, u32 mask)
+{
+ writel_relaxed(readl_relaxed(reg) | mask, reg);
+}
+
+static inline void st_i2c_clr_bits(void __iomem *reg, u32 mask)
+{
+ writel_relaxed(readl_relaxed(reg) & ~mask, reg);
+}
+
+/* From I2C Specifications v0.5 */
+static struct st_i2c_timings i2c_timings[] = {
+ [I2C_MODE_STANDARD] = {
+ .rate = 100000,
+ .rep_start_hold = 4000,
+ .rep_start_setup = 4700,
+ .start_hold = 4000,
+ .data_setup_time = 250,
+ .stop_setup_time = 4000,
+ .bus_free_time = 4700,
+ },
+ [I2C_MODE_FAST] = {
+ .rate = 400000,
+ .rep_start_hold = 600,
+ .rep_start_setup = 600,
+ .start_hold = 600,
+ .data_setup_time = 100,
+ .stop_setup_time = 600,
+ .bus_free_time = 1300,
+ },
+};
+
+static void st_i2c_flush_rx_fifo(struct st_i2c_dev *i2c_dev)
+{
+ int count, i;
+
+ /*
+ * Counter only counts up to 7 but fifo size is 8...
+ * When fifo is full, counter is 0 and RIR bit of status register is
+ * set
+ */
+ if (readl_relaxed(i2c_dev->base + SSC_STA) & SSC_STA_RIR)
+ count = SSC_RXFIFO_SIZE;
+ else
+ count = readl_relaxed(i2c_dev->base + SSC_RX_FSTAT) &
+ SSC_RX_FSTAT_STATUS;
+
+ for (i = 0; i < count; i++)
+ readl_relaxed(i2c_dev->base + SSC_RBUF);
+}
+
+static void st_i2c_soft_reset(struct st_i2c_dev *i2c_dev)
+{
+ /*
+ * FIFO needs to be emptied before reseting the IP,
+ * else the controller raises a BUSY error.
+ */
+ st_i2c_flush_rx_fifo(i2c_dev);
+
+ st_i2c_set_bits(i2c_dev->base + SSC_CTL, SSC_CTL_SR);
+ st_i2c_clr_bits(i2c_dev->base + SSC_CTL, SSC_CTL_SR);
+}
+
+/**
+ * st_i2c_hw_config() - Prepare SSC block, calculate and apply tuning timings
+ * @i2c_dev: Controller's private data
+ */
+static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev)
+{
+ unsigned long rate;
+ u32 val, ns_per_clk;
+ struct st_i2c_timings *t = &i2c_timings[i2c_dev->mode];
+
+ st_i2c_soft_reset(i2c_dev);
+
+ val = SSC_CLR_REPSTRT | SSC_CLR_NACK | SSC_CLR_SSCARBL |
+ SSC_CLR_SSCAAS | SSC_CLR_SSCSTOP;
+ writel_relaxed(val, i2c_dev->base + SSC_CLR);
+
+ /* SSC Control register setup */
+ val = SSC_CTL_PO | SSC_CTL_PH | SSC_CTL_HB | SSC_CTL_DATA_WIDTH_9;
+ writel_relaxed(val, i2c_dev->base + SSC_CTL);
+
+ rate = clk_get_rate(i2c_dev->clk);
+ ns_per_clk = 1000000000 / rate;
+
+ /* Baudrate */
+ val = rate / (2 * t->rate);
+ writel_relaxed(val, i2c_dev->base + SSC_BRG);
+
+ /* Pre-scaler baudrate */
+ writel_relaxed(1, i2c_dev->base + SSC_PRE_SCALER_BRG);
+
+ /* Enable I2C mode */
+ writel_relaxed(SSC_I2C_I2CM, i2c_dev->base + SSC_I2C);
+
+ /* Repeated start hold time */
+ val = t->rep_start_hold / ns_per_clk;
+ writel_relaxed(val, i2c_dev->base + SSC_REP_START_HOLD);
+
+ /* Repeated start set up time */
+ val = t->rep_start_setup / ns_per_clk;
+ writel_relaxed(val, i2c_dev->base + SSC_REP_START_SETUP);
+
+ /* Start hold time */
+ val = t->start_hold / ns_per_clk;
+ writel_relaxed(val, i2c_dev->base + SSC_START_HOLD);
+
+ /* Data set up time */
+ val = t->data_setup_time / ns_per_clk;
+ writel_relaxed(val, i2c_dev->base + SSC_DATA_SETUP);
+
+ /* Stop set up time */
+ val = t->stop_setup_time / ns_per_clk;
+ writel_relaxed(val, i2c_dev->base + SSC_STOP_SETUP);
+
+ /* Bus free time */
+ val = t->bus_free_time / ns_per_clk;
+ writel_relaxed(val, i2c_dev->base + SSC_BUS_FREE);
+
+ /* Prescalers set up */
+ val = rate / 10000000;
+ writel_relaxed(val, i2c_dev->base + SSC_PRSCALER);
+ writel_relaxed(val, i2c_dev->base + SSC_PRSCALER_DATAOUT);
+
+ /* Noise suppression witdh */
+ val = i2c_dev->scl_min_width_us * rate / 100000000;
+ writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH);
+
+ /* Noise suppression max output data delay width */
+ val = i2c_dev->sda_min_width_us * rate / 100000000;
+ writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT);
+}
+
+static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
+{
+ u32 sta;
+ int i;
+
+ for (i = 0; i < 10; i++) {
+ sta = readl_relaxed(i2c_dev->base + SSC_STA);
+ if (!(sta & SSC_STA_BUSY))
+ return 0;
+
+ usleep_range(2000, 4000);
+ }
+
+ dev_err(i2c_dev->dev, "bus not free (status = 0x%08x)\n", sta);
+
+ return -EBUSY;
+}
+
+/**
+ * st_i2c_write_tx_fifo() - Write a byte in the Tx FIFO
+ * @i2c_dev: Controller's private data
+ * @byte: Data to write in the Tx FIFO
+ */
+static inline void st_i2c_write_tx_fifo(struct st_i2c_dev *i2c_dev, u8 byte)
+{
+ u16 tbuf = byte << 1;
+
+ writel_relaxed(tbuf | 1, i2c_dev->base + SSC_TBUF);
+}
+
+/**
+ * st_i2c_wr_fill_tx_fifo() - Fill the Tx FIFO in write mode
+ * @i2c_dev: Controller's private data
+ *
+ * This functions fills the Tx FIFO with I2C transfert buffer when
+ * in write mode.
+ */
+static void st_i2c_wr_fill_tx_fifo(struct st_i2c_dev *i2c_dev)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+ u32 tx_fstat, sta;
+ int i;
+
+ sta = readl_relaxed(i2c_dev->base + SSC_STA);
+ if (sta & SSC_STA_TX_FIFO_FULL)
+ return;
+
+ tx_fstat = readl_relaxed(i2c_dev->base + SSC_TX_FSTAT);
+ tx_fstat &= SSC_TX_FSTAT_STATUS;
+
+ if (c->count < (SSC_TXFIFO_SIZE - tx_fstat))
+ i = c->count;
+ else
+ i = SSC_TXFIFO_SIZE - tx_fstat;
+
+ for (; i > 0; i--, c->count--, c->buf++)
+ st_i2c_write_tx_fifo(i2c_dev, *c->buf);
+}
+
+/**
+ * st_i2c_rd_fill_tx_fifo() - Fill the Tx FIFO in read mode
+ * @i2c_dev: Controller's private data
+ *
+ * This functions fills the Tx FIFO with fixed pattern when
+ * in read mode to trigger clock.
+ */
+static void st_i2c_rd_fill_tx_fifo(struct st_i2c_dev *i2c_dev, int max)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+ u32 tx_fstat, sta;
+ int i;
+
+ sta = readl_relaxed(i2c_dev->base + SSC_STA);
+ if (sta & SSC_STA_TX_FIFO_FULL)
+ return;
+
+ tx_fstat = readl_relaxed(i2c_dev->base + SSC_TX_FSTAT);
+ tx_fstat &= SSC_TX_FSTAT_STATUS;
+
+ if (max < (SSC_TXFIFO_SIZE - tx_fstat))
+ i = max;
+ else
+ i = SSC_TXFIFO_SIZE - tx_fstat;
+
+ for (; i > 0; i--, c->xfered++)
+ st_i2c_write_tx_fifo(i2c_dev, 0xff);
+}
+
+static void st_i2c_read_rx_fifo(struct st_i2c_dev *i2c_dev)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+ u32 i, sta;
+ u16 rbuf;
+
+ sta = readl_relaxed(i2c_dev->base + SSC_STA);
+ if (sta & SSC_STA_RIR) {
+ i = SSC_RXFIFO_SIZE;
+ } else {
+ i = readl_relaxed(i2c_dev->base + SSC_RX_FSTAT);
+ i &= SSC_RX_FSTAT_STATUS;
+ }
+
+ for (; (i > 0) && (c->count > 0); i--, c->count--) {
+ rbuf = readl_relaxed(i2c_dev->base + SSC_RBUF) >> 1;
+ *c->buf++ = (u8)rbuf & 0xff;
+ }
+
+ if (i) {
+ dev_err(i2c_dev->dev, "Unexpected %d bytes in rx fifo\n", i);
+ st_i2c_flush_rx_fifo(i2c_dev);
+ }
+}
+
+/**
+ * st_i2c_terminate_xfer() - Send either STOP or REPSTART condition
+ * @i2c_dev: Controller's private data
+ */
+static void st_i2c_terminate_xfer(struct st_i2c_dev *i2c_dev)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+
+ st_i2c_clr_bits(i2c_dev->base + SSC_IEN, SSC_IEN_TEEN);
+ st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STRTG);
+
+ if (c->stop) {
+ st_i2c_set_bits(i2c_dev->base + SSC_IEN, SSC_IEN_STOPEN);
+ st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
+ } else {
+ st_i2c_set_bits(i2c_dev->base + SSC_IEN, SSC_IEN_REPSTRTEN);
+ st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_REPSTRTG);
+ }
+}
+
+/**
+ * st_i2c_handle_write() - Handle FIFO empty interrupt in case of write
+ * @i2c_dev: Controller's private data
+ */
+static void st_i2c_handle_write(struct st_i2c_dev *i2c_dev)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+
+ st_i2c_flush_rx_fifo(i2c_dev);
+
+ if (!c->count)
+ /* End of xfer, send stop or repstart */
+ st_i2c_terminate_xfer(i2c_dev);
+ else
+ st_i2c_wr_fill_tx_fifo(i2c_dev);
+}
+
+/**
+ * st_i2c_handle_write() - Handle FIFO enmpty interrupt in case of read
+ * @i2c_dev: Controller's private data
+ */
+static void st_i2c_handle_read(struct st_i2c_dev *i2c_dev)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+ u32 ien;
+
+ /* Trash the address read back */
+ if (!c->xfered) {
+ readl_relaxed(i2c_dev->base + SSC_RBUF);
+ st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_TXENB);
+ } else {
+ st_i2c_read_rx_fifo(i2c_dev);
+ }
+
+ if (!c->count) {
+ /* End of xfer, send stop or repstart */
+ st_i2c_terminate_xfer(i2c_dev);
+ } else if (c->count == 1) {
+ /* Penultimate byte to xfer, disable ACK gen. */
+ st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_ACKG);
+
+ /* Last received byte is to be handled by NACK interrupt */
+ ien = SSC_IEN_NACKEN | SSC_IEN_ARBLEN;
+ writel_relaxed(ien, i2c_dev->base + SSC_IEN);
+
+ st_i2c_rd_fill_tx_fifo(i2c_dev, c->count);
+ } else {
+ st_i2c_rd_fill_tx_fifo(i2c_dev, c->count - 1);
+ }
+}
+
+/**
+ * st_i2c_isr() - Interrupt routine
+ * @irq: interrupt number
+ * @data: Controller's private data
+ */
+static irqreturn_t st_i2c_isr_thread(int irq, void *data)
+{
+ struct st_i2c_dev *i2c_dev = data;
+ struct st_i2c_client *c = &i2c_dev->client;
+ u32 sta, ien;
+ int it;
+
+ ien = readl_relaxed(i2c_dev->base + SSC_IEN);
+ sta = readl_relaxed(i2c_dev->base + SSC_STA);
+
+ /* Use __fls() to check error bits first */
+ it = __fls(sta & ien);
+ if (it < 0) {
+ dev_dbg(i2c_dev->dev, "spurious it (sta=0x%04x, ien=0x%04x)\n",
+ sta, ien);
+ return IRQ_NONE;
+ }
+
+ switch (1 << it) {
+ case SSC_STA_TE:
+ if (c->addr & I2C_M_RD)
+ st_i2c_handle_read(i2c_dev);
+ else
+ st_i2c_handle_write(i2c_dev);
+ break;
+
+ case SSC_STA_STOP:
+ case SSC_STA_REPSTRT:
+ writel_relaxed(0, i2c_dev->base + SSC_IEN);
+ complete(&i2c_dev->complete);
+ break;
+
+ case SSC_STA_NACK:
+ writel_relaxed(SSC_CLR_NACK, i2c_dev->base + SSC_CLR);
+
+ /* Last received byte handled by NACK interrupt */
+ if ((c->addr & I2C_M_RD) && (c->count == 1) && (c->xfered)) {
+ st_i2c_handle_read(i2c_dev);
+ break;
+ }
+
+ it = SSC_IEN_STOPEN | SSC_IEN_ARBLEN;
+ writel_relaxed(it, i2c_dev->base + SSC_IEN);
+
+ st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
+ c->result = -EIO;
+ break;
+
+ case SSC_STA_ARBL:
+ writel_relaxed(SSC_CLR_SSCARBL, i2c_dev->base + SSC_CLR);
+
+ it = SSC_IEN_STOPEN | SSC_IEN_ARBLEN;
+ writel_relaxed(it, i2c_dev->base + SSC_IEN);
+
+ st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
+ c->result = -EIO;
+ break;
+
+ default:
+ dev_err(i2c_dev->dev,
+ "it %d unhandled (sta=0x%04x)\n", it, sta);
+ }
+
+ /*
+ * Read IEN register to ensure interrupt mask write is effective
+ * before re-enabling interrupt at GIC level, and thus avoid spurious
+ * interrupts.
+ */
+ readl(i2c_dev->base + SSC_IEN);
+
+ return IRQ_HANDLED;
+}
+
+/**
+ * st_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 st_i2c_xfer_msg(struct st_i2c_dev *i2c_dev, struct i2c_msg *msg,
+ bool is_first, bool is_last)
+{
+ struct st_i2c_client *c = &i2c_dev->client;
+ u32 ctl, i2c, it;
+ unsigned long timeout;
+ int ret;
+
+ c->addr = (u8)(msg->addr << 1);
+ c->addr |= (msg->flags & I2C_M_RD);
+ c->buf = msg->buf;
+ c->count = msg->len;
+ c->xfered = 0;
+ c->result = 0;
+ c->stop = is_last;
+
+ INIT_COMPLETION(i2c_dev->complete);
+
+ ctl = SSC_CTL_EN | SSC_CTL_MS | SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO;
+ st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl);
+
+ i2c = SSC_I2C_TXENB;
+ if (c->addr & I2C_M_RD)
+ i2c |= SSC_I2C_ACKG;
+ st_i2c_set_bits(i2c_dev->base + SSC_I2C, i2c);
+
+ /* Write slave address */
+ st_i2c_write_tx_fifo(i2c_dev, c->addr);
+
+ /* Pre-fill Tx fifo with data in case of write */
+ if (!(c->addr & I2C_M_RD))
+ st_i2c_wr_fill_tx_fifo(i2c_dev);
+
+ it = SSC_IEN_NACKEN | SSC_IEN_TEEN | SSC_IEN_ARBLEN;
+ writel_relaxed(it, i2c_dev->base + SSC_IEN);
+
+ if (is_first) {
+ ret = st_i2c_wait_free_bus(i2c_dev);
+ if (ret)
+ return ret;
+
+ st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STRTG);
+ }
+
+ timeout = wait_for_completion_timeout(&i2c_dev->complete,
+ i2c_dev->adap.timeout);
+ ret = c->result;
+
+ if (!timeout) {
+ dev_err(i2c_dev->dev, "Write to slave 0x%x timed out\n",
+ c->addr);
+ ret = -ETIMEDOUT;
+ }
+
+ i2c = SSC_I2C_STOPG | SSC_I2C_REPSTRTG;
+ st_i2c_clr_bits(i2c_dev->base + SSC_I2C, i2c);
+
+ writel_relaxed(SSC_CLR_SSCSTOP | SSC_CLR_REPSTRT,
+ i2c_dev->base + SSC_CLR);
+
+ return ret;
+}
+
+/**
+ * st_i2c_xfer() - Transfer a single 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 st_i2c_xfer(struct i2c_adapter *i2c_adap,
+ struct i2c_msg msgs[], int num)
+{
+ struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
+ int ret, i;
+
+ i2c_dev->busy = true;
+
+ ret = clk_prepare_enable(i2c_dev->clk);
+ if (ret) {
+ dev_err(i2c_dev->dev, "Failed to prepare_enable clock\n");
+ return ret;
+ }
+
+ pinctrl_pm_select_default_state(i2c_dev->dev);
+
+ st_i2c_hw_config(i2c_dev);
+
+ for (i = 0; (i < num) && !ret; i++)
+ ret = st_i2c_xfer_msg(i2c_dev, &msgs[i], i == 0, i == num - 1);
+
+ pinctrl_pm_select_idle_state(i2c_dev->dev);
+
+ clk_disable_unprepare(i2c_dev->clk);
+
+ i2c_dev->busy = false;
+
+ return (ret < 0) ? ret : i;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int st_i2c_suspend(struct device *dev)
+{
+ struct platform_device *pdev =
+ container_of(dev, struct platform_device, dev);
+ struct st_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+
+ if (i2c_dev->busy)
+ return -EBUSY;
+
+ pinctrl_pm_select_sleep_state(dev);
+
+ return 0;
+}
+
+static int st_i2c_resume(struct device *dev)
+{
+ pinctrl_pm_select_default_state(dev);
+ /* Go in idle state if available */
+ pinctrl_pm_select_idle_state(dev);
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(st_i2c_pm, st_i2c_suspend, st_i2c_resume);
+#define ST_I2C_PM (&st_i2c_pm)
+#else
+#define ST_I2C_PM NULL
+#endif
+
+static u32 st_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm st_i2c_algo = {
+ .master_xfer = st_i2c_xfer,
+ .functionality = st_i2c_func,
+};
+
+static int st_i2c_of_get_deglitch(struct device_node *np,
+ struct st_i2c_dev *i2c_dev)
+{
+ int ret;
+
+ ret = of_property_read_u32(np, "st,i2c-min-scl-pulse-width-us",
+ &i2c_dev->scl_min_width_us);
+ if ((ret == -ENODATA) || (ret == -EOVERFLOW)) {
+ dev_err(i2c_dev->dev, "st,i2c-min-scl-pulse-width-us invalid\n");
+ return ret;
+ }
+
+ ret = of_property_read_u32(np, "st,i2c-min-sda-pulse-width-us",
+ &i2c_dev->sda_min_width_us);
+ if ((ret == -ENODATA) || (ret == -EOVERFLOW)) {
+ dev_err(i2c_dev->dev, "st,i2c-min-sda-pulse-width-us invalid\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int st_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct st_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 = irq_of_parse_and_map(np, 0);
+ if (!i2c_dev->irq) {
+ dev_err(&pdev->dev, "IRQ missing or invalid\n");
+ return -EINVAL;
+ }
+
+ i2c_dev->clk = of_clk_get_by_name(np, "ssc");
+ if (IS_ERR(i2c_dev->clk)) {
+ dev_err(&pdev->dev, "Unable to request clock\n");
+ return PTR_ERR(i2c_dev->clk);
+ }
+
+ i2c_dev->mode = I2C_MODE_STANDARD;
+ ret = of_property_read_u32(np, "clock-frequency", &clk_rate);
+ if ((!ret) && (clk_rate == 400000))
+ i2c_dev->mode = I2C_MODE_FAST;
+
+ i2c_dev->dev = &pdev->dev;
+
+ ret = devm_request_threaded_irq(&pdev->dev, i2c_dev->irq,
+ NULL, st_i2c_isr_thread,
+ IRQF_ONESHOT, pdev->name, i2c_dev);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
+ return ret;
+ }
+
+ pinctrl_pm_select_default_state(i2c_dev->dev);
+ /* In case idle state available, select it */
+ pinctrl_pm_select_idle_state(i2c_dev->dev);
+
+ ret = st_i2c_of_get_deglitch(np, i2c_dev);
+ if (ret)
+ return ret;
+
+ adap = &i2c_dev->adap;
+ i2c_set_adapdata(adap, i2c_dev);
+ snprintf(adap->name, sizeof(adap->name), "ST I2C(0x%x)", res->start);
+ adap->owner = THIS_MODULE;
+ adap->timeout = 2 * HZ;
+ adap->retries = 0;
+ adap->algo = &st_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");
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, i2c_dev);
+
+ dev_info(i2c_dev->dev, "%s initialized\n", adap->name);
+
+ return 0;
+}
+
+static int st_i2c_remove(struct platform_device *pdev)
+{
+ struct st_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&i2c_dev->adap);
+
+ return 0;
+}
+
+static struct of_device_id st_i2c_match[] = {
+ { .compatible = "st,comms-ssc-i2c", },
+ { .compatible = "st,comms-ssc4-i2c", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, st_i2c_match);
+
+static struct platform_driver st_i2c_driver = {
+ .driver = {
+ .name = "st-i2c",
+ .owner = THIS_MODULE,
+ .of_match_table = st_i2c_match,
+ .pm = ST_I2C_PM,
+ },
+ .probe = st_i2c_probe,
+ .remove = st_i2c_remove,
+};
+
+module_platform_driver(st_i2c_driver);
+
+MODULE_AUTHOR("Maxime Coquelin <maxime.coquelin at st.com>");
+MODULE_DESCRIPTION("STMicroelectronics I2C driver");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5
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