i2c: atmel: add i2c driver

Add i2c driver.

Signed-off-by: Songjun Wu <songjun.wu@atmel.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Acked-by: Heiko Schocher <hs@denx.de>

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

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

drivers/i2c/at91_i2c.c

@@ -0,0 +1,338 @@
+/*
+ * Atmel I2C driver.
+ *
+ * (C) Copyright 2016 Songjun Wu <songjun.wu@atmel.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <asm/io.h>
+#include <common.h>
+#include <clk_client.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(&reg->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(&reg->sr);
+	if (is_read) {
+		writel(TWI_CR_START, &reg->cr);
+
+		for (i = 0; !ret && i < (msg->len - 1); i++) {
+			ret = at91_wait_for_xfer(bus, TWI_SR_RXRDY);
+			msg->buf[i] = readl(&reg->rhr);
+		}
+
+		if (ret)
+			goto error;
+
+		writel(TWI_CR_STOP, &reg->cr);
+
+		ret = at91_wait_for_xfer(bus, TWI_SR_RXRDY);
+		if (ret)
+			goto error;
+
+		msg->buf[i] = readl(&reg->rhr);
+
+	} else {
+		writel(msg->buf[0], &reg->thr);
+		for (i = 1; !ret && (i < msg->len); i++) {
+			writel(msg->buf[i], &reg->thr);
+			ret = at91_wait_for_xfer(bus, TWI_SR_TXRDY);
+		}
+
+		if (ret)
+			goto error;
+
+		writel(TWI_CR_STOP, &reg->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, &reg->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, &reg->iadr);
+	}
+
+	is_read = m_start->flags & I2C_M_RD;
+
+	writel((m_start->addr << 16) | int_addr_flag |
+	       (is_read ? TWI_MMR_MREAD : 0), &reg->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 *dev_clk;
+	struct clk clk;
+	ulong clk_rate;
+	int periph;
+	int ret;
+
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return -EINVAL;
+
+	periph = fdtdec_get_uint(gd->fdt_blob, clk.dev->of_offset, "reg", -1);
+	if (periph < 0)
+		return -EINVAL;
+
+	dev_clk = dev_get_parent(clk.dev);
+	ret = clk_request(dev_clk, &clk);
+	if (ret)
+		return ret;
+
+	clk.id = periph;
+	ret = clk_enable(&clk);
+	if (ret)
+		return ret;
+
+	ret = clk_get_by_index(dev_clk, 0, &clk);
+	if (ret)
+		return ret;
+
+	clk_rate = clk_get_rate(&clk);
+	if (!clk_rate)
+		return -ENODEV;
+
+	bus->bus_clk_rate = clk_rate;
+
+	clk_free(&clk);
+
+	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, &reg->cr);
+
+	at91_calc_i2c_clock(dev, bus->clock_frequency);
+
+	writel(bus->cwgr_val, &reg->cwgr);
+	writel(TWI_CR_MSEN, &reg->cr);
+	writel(TWI_CR_SVDIS, &reg->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,
+};

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