[U-Boot] [PATCH v2 1/2] i2c: atmel: add i2c driver
Songjun Wu
songjun.wu at atmel.com
Wed Jun 1 08:18:57 CEST 2016
Add i2c driver.
Signed-off-by: Songjun Wu <songjun.wu at atmel.com>
---
Changes in v2:
- Add code to get and enable clock.
drivers/i2c/Kconfig | 10 ++
drivers/i2c/Makefile | 1 +
drivers/i2c/at91_i2c.c | 345 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/i2c/at91_i2c.h | 77 +++++++++++
4 files changed, 433 insertions(+)
create mode 100644 drivers/i2c/at91_i2c.c
create mode 100644 drivers/i2c/at91_i2c.h
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 6e22bba..f6a613c 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -58,6 +58,16 @@ config DM_I2C_GPIO
bindings are supported.
Binding info: doc/device-tree-bindings/i2c/i2c-gpio.txt
+config SYS_I2C_AT91
+ bool "Atmel I2C driver"
+ depends on DM_I2C && ARCH_AT91
+ help
+ Add support for the Atmel I2C driver. A serious problem is that there
+ is no documented way to issue repeated START conditions for more than
+ two messages, as needed to support combined I2C messages. Use the
+ i2c-gpio driver unless your system can cope with this limitation.
+ Binding info: doc/device-tree-bindings/i2c/i2c-at91.txt
+
config SYS_I2C_FSL
bool "Freescale I2C bus driver"
depends on DM_I2C
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 167424d..c5362a5 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_PCA9564_I2C) += pca9564_i2c.o
obj-$(CONFIG_TSI108_I2C) += tsi108_i2c.o
obj-$(CONFIG_SH_SH7734_I2C) += sh_sh7734_i2c.o
obj-$(CONFIG_SYS_I2C) += i2c_core.o
+obj-$(CONFIG_SYS_I2C_AT91) += at91_i2c.o
obj-$(CONFIG_SYS_I2C_CADENCE) += i2c-cdns.o
obj-$(CONFIG_SYS_I2C_DAVINCI) += davinci_i2c.o
obj-$(CONFIG_SYS_I2C_DW) += designware_i2c.o
diff --git a/drivers/i2c/at91_i2c.c b/drivers/i2c/at91_i2c.c
new file mode 100644
index 0000000..7beffb3
--- /dev/null
+++ b/drivers/i2c/at91_i2c.c
@@ -0,0 +1,345 @@
+/*
+ * Atmel I2C driver.
+ *
+ * (C) Copyright 2016 Songjun Wu <songjun.wu at atmel.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <asm/io.h>
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <linux/bitops.h>
+#include <mach/clk.h>
+
+#include "at91_i2c.h"
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define I2C_TIMEOUT_MS 100
+
+static int at91_wait_for_xfer(struct at91_i2c_bus *bus, u32 status)
+{
+ struct at91_i2c_regs *reg = bus->regs;
+ ulong start_time = get_timer(0);
+ u32 sr;
+
+ bus->status = 0;
+
+ do {
+ sr = readl(®->sr);
+ bus->status |= sr;
+
+ if (sr & TWI_SR_NACK)
+ return -EREMOTEIO;
+ else if (sr & status)
+ return 0;
+ } while (get_timer(start_time) < I2C_TIMEOUT_MS);
+
+ return -ETIMEDOUT;
+}
+
+static int at91_i2c_xfer_msg(struct at91_i2c_bus *bus, struct i2c_msg *msg)
+{
+ struct at91_i2c_regs *reg = bus->regs;
+ bool is_read = msg->flags & I2C_M_RD;
+ u32 i;
+ int ret = 0;
+
+ readl(®->sr);
+ if (is_read) {
+ writel(TWI_CR_START, ®->cr);
+
+ for (i = 0; !ret && i < (msg->len - 1); i++) {
+ ret = at91_wait_for_xfer(bus, TWI_SR_RXRDY);
+ msg->buf[i] = readl(®->rhr);
+ }
+
+ if (ret)
+ goto error;
+
+ writel(TWI_CR_STOP, ®->cr);
+
+ ret = at91_wait_for_xfer(bus, TWI_SR_RXRDY);
+ if (ret)
+ goto error;
+
+ msg->buf[i] = readl(®->rhr);
+
+ } else {
+ writel(msg->buf[0], ®->thr);
+ for (i = 1; !ret && (i < msg->len); i++) {
+ writel(msg->buf[i], ®->thr);
+ ret = at91_wait_for_xfer(bus, TWI_SR_TXRDY);
+ }
+
+ if (ret)
+ goto error;
+
+ writel(TWI_CR_STOP, ®->cr);
+ }
+
+ if (!ret)
+ ret = at91_wait_for_xfer(bus, TWI_SR_TXCOMP);
+
+ if (ret)
+ goto error;
+
+ if (bus->status & (TWI_SR_OVRE | TWI_SR_UNRE | TWI_SR_LOCK)) {
+ ret = -EIO;
+ goto error;
+ }
+
+ return 0;
+
+error:
+ if (bus->status & TWI_SR_LOCK)
+ writel(TWI_CR_LOCKCLR, ®->cr);
+
+ return ret;
+}
+
+static int at91_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
+{
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+ struct at91_i2c_regs *reg = bus->regs;
+ struct i2c_msg *m_start = msg;
+ bool is_read;
+ u32 int_addr_flag = 0;
+ int ret = 0;
+
+ if (nmsgs == 2) {
+ int internal_address = 0;
+ int i;
+
+ /* 1st msg is put into the internal address, start with 2nd */
+ m_start = &msg[1];
+
+ /* the max length of internal address is 3 bytes */
+ if (msg->len > 3)
+ return -EFAULT;
+
+ for (i = 0; i < msg->len; ++i) {
+ const unsigned addr = msg->buf[msg->len - 1 - i];
+
+ internal_address |= addr << (8 * i);
+ int_addr_flag += TWI_MMR_IADRSZ_1;
+ }
+
+ writel(internal_address, ®->iadr);
+ }
+
+ is_read = m_start->flags & I2C_M_RD;
+
+ writel((m_start->addr << 16) | int_addr_flag |
+ (is_read ? TWI_MMR_MREAD : 0), ®->mmr);
+
+ ret = at91_i2c_xfer_msg(bus, m_start);
+
+ return ret;
+}
+
+/*
+ * Calculate symmetric clock as stated in datasheet:
+ * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))
+ */
+static void at91_calc_i2c_clock(struct udevice *dev, int i2c_clk)
+{
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+ const struct at91_i2c_pdata *pdata = bus->pdata;
+ int offset = pdata->clk_offset;
+ int max_ckdiv = pdata->clk_max_div;
+ int ckdiv, cdiv, div;
+ unsigned long src_rate;
+
+ src_rate = bus->bus_clk_rate;
+
+ div = max(0, (int)DIV_ROUND_UP(src_rate, 2 * i2c_clk) - offset);
+ ckdiv = fls(div >> 8);
+ cdiv = div >> ckdiv;
+
+ if (ckdiv > max_ckdiv) {
+ ckdiv = max_ckdiv;
+ cdiv = 255;
+ }
+
+ bus->speed = DIV_ROUND_UP(src_rate,
+ (cdiv * (1 << ckdiv) + offset) * 2);
+
+ bus->cwgr_val = (ckdiv << 16) | (cdiv << 8) | cdiv;
+}
+
+static int at91_i2c_enable_clk(struct udevice *dev)
+{
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+ struct udevice *clkdev;
+ ulong clk_rate;
+ int periph;
+ int ret;
+
+ ret = clk_get_by_index(dev, 0, &clkdev);
+ if (ret) {
+ dev_err(dev, "Failed to find peripheral clock node\n");
+ return -EINVAL;
+ }
+
+ periph = fdtdec_get_uint(gd->fdt_blob, clkdev->of_offset, "reg", -1);
+ if (periph < 0) {
+ dev_err(dev, "Failed to find peripheral id\n");
+ return -EINVAL;
+ }
+
+ clkdev = dev_get_parent(clkdev);
+ if (!clkdev) {
+ dev_err(dev, "Failed to find parent node\n");
+ return -ENODEV;
+ }
+
+ ret = clk_enable(clkdev, periph);
+ if (ret) {
+ dev_err(dev, "Failed to enable peripheral clock\n");
+ return ret;
+ }
+
+ ret = clk_get_by_index(clkdev, 0, &clkdev);
+ if (ret) {
+ dev_err(dev, "Failed to find bus clock node\n");
+ return ret;
+ }
+
+ clk_rate = clk_get_rate(clkdev);
+ if (!clk_rate) {
+ dev_err(dev, "Failed to get bus clock rate\n");
+ return -ENODEV;
+ }
+
+ bus->bus_clk_rate = clk_rate;
+
+ return 0;
+}
+
+static int at91_i2c_probe(struct udevice *dev, uint chip, uint chip_flags)
+{
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+ struct at91_i2c_regs *reg = bus->regs;
+ int ret;
+
+ ret = at91_i2c_enable_clk(dev);
+ if (ret)
+ return ret;
+
+ writel(TWI_CR_SWRST, ®->cr);
+
+ at91_calc_i2c_clock(dev, bus->clock_frequency);
+
+ writel(bus->cwgr_val, ®->cwgr);
+ writel(TWI_CR_MSEN, ®->cr);
+ writel(TWI_CR_SVDIS, ®->cr);
+
+ return 0;
+}
+
+static int at91_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
+{
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+
+ at91_calc_i2c_clock(dev, speed);
+
+ writel(bus->cwgr_val, &bus->regs->cwgr);
+
+ return 0;
+}
+
+int at91_i2c_get_bus_speed(struct udevice *dev)
+{
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+
+ return bus->speed;
+}
+
+static int at91_i2c_ofdata_to_platdata(struct udevice *dev)
+{
+ const void *blob = gd->fdt_blob;
+ struct at91_i2c_bus *bus = dev_get_priv(dev);
+ int node = dev->of_offset;
+
+ bus->regs = (struct at91_i2c_regs *)dev_get_addr(dev);
+ bus->pdata = (struct at91_i2c_pdata *)dev_get_driver_data(dev);
+ bus->clock_frequency = fdtdec_get_int(blob, node,
+ "clock-frequency", 100000);
+
+ return 0;
+}
+
+static const struct dm_i2c_ops at91_i2c_ops = {
+ .xfer = at91_i2c_xfer,
+ .probe_chip = at91_i2c_probe,
+ .set_bus_speed = at91_i2c_set_bus_speed,
+ .get_bus_speed = at91_i2c_get_bus_speed,
+};
+
+static const struct at91_i2c_pdata at91rm9200_config = {
+ .clk_max_div = 5,
+ .clk_offset = 3,
+};
+
+static const struct at91_i2c_pdata at91sam9261_config = {
+ .clk_max_div = 5,
+ .clk_offset = 4,
+};
+
+static const struct at91_i2c_pdata at91sam9260_config = {
+ .clk_max_div = 7,
+ .clk_offset = 4,
+};
+
+static const struct at91_i2c_pdata at91sam9g20_config = {
+ .clk_max_div = 7,
+ .clk_offset = 4,
+};
+
+static const struct at91_i2c_pdata at91sam9g10_config = {
+ .clk_max_div = 7,
+ .clk_offset = 4,
+};
+
+static const struct at91_i2c_pdata at91sam9x5_config = {
+ .clk_max_div = 7,
+ .clk_offset = 4,
+};
+
+static const struct at91_i2c_pdata sama5d4_config = {
+ .clk_max_div = 7,
+ .clk_offset = 4,
+};
+
+static const struct at91_i2c_pdata sama5d2_config = {
+ .clk_max_div = 7,
+ .clk_offset = 3,
+};
+
+static const struct udevice_id at91_i2c_ids[] = {
+{ .compatible = "atmel,at91rm9200-i2c", .data = (long)&at91rm9200_config },
+{ .compatible = "atmel,at91sam9260-i2c", .data = (long)&at91sam9260_config },
+{ .compatible = "atmel,at91sam9261-i2c", .data = (long)&at91sam9261_config },
+{ .compatible = "atmel,at91sam9g20-i2c", .data = (long)&at91sam9g20_config },
+{ .compatible = "atmel,at91sam9g10-i2c", .data = (long)&at91sam9g10_config },
+{ .compatible = "atmel,at91sam9x5-i2c", .data = (long)&at91sam9x5_config },
+{ .compatible = "atmel,sama5d4-i2c", .data = (long)&sama5d4_config },
+{ .compatible = "atmel,sama5d2-i2c", .data = (long)&sama5d2_config },
+{ }
+};
+
+U_BOOT_DRIVER(i2c_at91) = {
+ .name = "i2c_at91",
+ .id = UCLASS_I2C,
+ .of_match = at91_i2c_ids,
+ .ofdata_to_platdata = at91_i2c_ofdata_to_platdata,
+ .per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
+ .priv_auto_alloc_size = sizeof(struct at91_i2c_bus),
+ .ops = &at91_i2c_ops,
+};
diff --git a/drivers/i2c/at91_i2c.h b/drivers/i2c/at91_i2c.h
new file mode 100644
index 0000000..87f02bf
--- /dev/null
+++ b/drivers/i2c/at91_i2c.h
@@ -0,0 +1,77 @@
+#ifndef _AT91_I2C_H
+#define _AT91_I2C_H
+
+#define TWI_CR_START BIT(0) /* Send a Start Condition */
+#define TWI_CR_MSEN BIT(2) /* Master Transfer Enable */
+#define TWI_CR_STOP BIT(1) /* Send a Stop Condition */
+#define TWI_CR_SVDIS BIT(5) /* Slave Transfer Disable */
+#define TWI_CR_SWRST BIT(7) /* Software Reset */
+#define TWI_CR_ACMEN BIT(16) /* Alternative Command Mode Enable */
+#define TWI_CR_ACMDIS BIT(17) /* Alternative Command Mode Disable */
+#define TWI_CR_LOCKCLR BIT(26) /* Lock Clear */
+
+#define TWI_MMR_MREAD BIT(12) /* Master Read Direction */
+#define TWI_MMR_IADRSZ_1 BIT(8) /* Internal Device Address Size */
+
+#define TWI_SR_TXCOMP BIT(0) /* Transmission Complete */
+#define TWI_SR_RXRDY BIT(1) /* Receive Holding Register Ready */
+#define TWI_SR_TXRDY BIT(2) /* Transmit Holding Register Ready */
+#define TWI_SR_OVRE BIT(6) /* Overrun Error */
+#define TWI_SR_UNRE BIT(7) /* Underrun Error */
+#define TWI_SR_NACK BIT(8) /* Not Acknowledged */
+#define TWI_SR_LOCK BIT(23) /* TWI Lock due to Frame Errors */
+
+#define TWI_ACR_DATAL(len) ((len) & 0xff)
+#define TWI_ACR_DIR_READ BIT(8)
+
+#define TWI_CWGR_HOLD_MAX 0x1f
+#define TWI_CWGR_HOLD(x) (((x) & TWI_CWGR_HOLD_MAX) << 24)
+
+struct at91_i2c_regs {
+ u32 cr;
+ u32 mmr;
+ u32 smr;
+ u32 iadr;
+ u32 cwgr;
+ u32 rev_0[3];
+ u32 sr;
+ u32 ier;
+ u32 idr;
+ u32 imr;
+ u32 rhr;
+ u32 thr;
+ u32 smbtr;
+ u32 rev_1;
+ u32 acr;
+ u32 filtr;
+ u32 rev_2;
+ u32 swmr;
+ u32 fmr;
+ u32 flr;
+ u32 rev_3;
+ u32 fsr;
+ u32 fier;
+ u32 fidr;
+ u32 fimr;
+ u32 rev_4[29];
+ u32 wpmr;
+ u32 wpsr;
+ u32 rev_5[6];
+};
+
+struct at91_i2c_pdata {
+ unsigned clk_max_div;
+ unsigned clk_offset;
+};
+
+struct at91_i2c_bus {
+ struct at91_i2c_regs *regs;
+ u32 status;
+ ulong bus_clk_rate;
+ u32 clock_frequency;
+ u32 speed;
+ u32 cwgr_val;
+ const struct at91_i2c_pdata *pdata;
+};
+
+#endif
--
2.7.4
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