[U-Boot] [PATCH v2 1/4] i2c: UniPhier: add driver for UniPhier i2c controller

[Masahiro Yamada <yamada.m@jp.panasonic.com>]

This commit adds on-chip I2C driver used on some old Panasonic
UniPhier SoCs.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---

Changes in v2:
  - Fix a typo.  s/freqency/frequency/
  - Add some comments to explain the formula calculating
    wait time.
  - add comments on every register
  - skip stop condition if the next message is read

 drivers/i2c/Kconfig        |  14 +++
 drivers/i2c/Makefile       |   1 +
 drivers/i2c/i2c-uniphier.c | 233 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 248 insertions(+)
 create mode 100644 drivers/i2c/i2c-uniphier.c

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index e69de29..6a479ef 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -0,0 +1,14 @@
+config DM_I2C
+	bool "Enable Driver Model for I2C drivers"
+	depends on DM
+	help
+	  If you want to use driver model for I2C drivers, say Y.
+	  To use legacy I2C drivers, say N.
+
+config SYS_I2C_UNIPHIER
+	bool "UniPhier I2C driver"
+	depends on ARCH_UNIPHIER && DM_I2C
+	default y
+	help
+	  Support for Panasonic UniPhier I2C controller driver.  This I2C
+	  controller is used on PH1-LD4, PH1-sLD8 or older UniPhier SoCs.
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 6f3c86c..e2fcd24 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -31,4 +31,5 @@ obj-$(CONFIG_SYS_I2C_SANDBOX) += sandbox_i2c.o i2c-emul-uclass.o
 obj-$(CONFIG_SYS_I2C_SH) += sh_i2c.o
 obj-$(CONFIG_SYS_I2C_SOFT) += soft_i2c.o
 obj-$(CONFIG_SYS_I2C_TEGRA) += tegra_i2c.o
+obj-$(CONFIG_SYS_I2C_UNIPHIER) += i2c-uniphier.o
 obj-$(CONFIG_SYS_I2C_ZYNQ) += zynq_i2c.o
diff --git a/drivers/i2c/i2c-uniphier.c b/drivers/i2c/i2c-uniphier.c
new file mode 100644
index 0000000..5c39c3c
--- /dev/null
+++ b/drivers/i2c/i2c-uniphier.c
@@ -0,0 +1,233 @@
+/*
+ * Copyright (C) 2014 Panasonic Corporation
+ *   Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <linux/types.h>
+#include <asm/io.h>
+#include <asm/errno.h>
+#include <dm/device.h>
+#include <dm/root.h>
+#include <i2c.h>
+#include <fdtdec.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define I2C_DTRM	0x00	/* data transmission */
+#define		I2C_DTRM_STA	(1 << 10)
+#define		I2C_DTRM_STO	(1 << 9)
+#define		I2C_DTRM_NACK	(1 << 8)
+#define		I2C_DTRM_RD	(1 << 0)
+#define I2C_DREC	0x04	/* data reception */
+#define		I2C_DREC_STS	(1 << 12)
+#define		I2C_DREC_LRB	(1 << 11)
+#define		I2C_DREC_LAB	(1 << 9)
+#define I2C_MYAD	0x08	/* slave address */
+#define I2C_CLK		0x0c	/* clock frequency control */
+#define I2C_BRST	0x10	/* bus reset */
+#define		I2C_BRST_FOEN	(1 << 1)
+#define		I2C_BRST_BRST	(1 << 0)
+#define I2C_HOLD	0x14	/* hold time control */
+#define I2C_BSTS	0x18	/* bus status monitor */
+#define I2C_NOISE	0x1c	/* noise filter control */
+#define I2C_SETUP	0x20	/* setup time control */
+
+#define IOBUS_FREQ	100000000
+
+struct uniphier_i2c_dev {
+	void __iomem *base;		/* register base */
+	unsigned long input_clk;	/* master clock (Hz) */
+	unsigned long wait_us;		/* wait for every byte transfer (us) */
+};
+
+static int uniphier_i2c_probe(struct udevice *dev)
+{
+	fdt_addr_t addr;
+	fdt_size_t size;
+	struct uniphier_i2c_dev *priv = dev_get_priv(dev);
+
+	addr = fdtdec_get_addr_size(gd->fdt_blob, dev->of_offset, "reg", &size);
+
+	priv->base = map_sysmem(addr, size);
+
+	if (!priv->base)
+		return -ENOMEM;
+
+	priv->input_clk = IOBUS_FREQ;
+
+	/* deassert reset */
+	writel(0x3, priv->base + I2C_BRST);
+
+	return 0;
+}
+
+static int uniphier_i2c_remove(struct udevice *dev)
+{
+	struct uniphier_i2c_dev *priv = dev_get_priv(dev);
+
+	unmap_sysmem(priv->base);
+
+	return 0;
+}
+
+static int uniphier_i2c_child_pre_probe(struct udevice *dev)
+{
+	struct dm_i2c_chip *i2c_chip = dev_get_parentdata(dev);
+
+	if (dev->of_offset == -1)
+		return 0;
+	return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev->of_offset,
+					   i2c_chip);
+}
+
+static int send_and_recv_byte(struct uniphier_i2c_dev *dev, u32 dtrm)
+{
+	writel(dtrm, dev->base + I2C_DTRM);
+
+	/*
+	 * This controller only provides interruption to inform the completion
+	 * of each byte transfer.  (No status register to poll it.)
+	 * Unfortunately, U-Boot does not have a good support of interrupt.
+	 * Wait for a while.
+	 */
+	udelay(dev->wait_us);
+
+	return readl(dev->base + I2C_DREC);
+}
+
+static int send_byte(struct uniphier_i2c_dev *dev, u32 dtrm, bool *stop)
+{
+	int ret = 0;
+	u32 drec;
+
+	drec = send_and_recv_byte(dev, dtrm);
+
+	if (drec & I2C_DREC_LAB) {
+		debug("uniphier_i2c: bus arbitration failed\n");
+		*stop = false;
+		ret = -EREMOTEIO;
+	}
+	if (drec & I2C_DREC_LRB) {
+		debug("uniphier_i2c: slave did not return ACK\n");
+		ret = -EREMOTEIO;
+	}
+	return ret;
+}
+
+static int uniphier_i2c_transmit(struct uniphier_i2c_dev *dev, uint addr,
+				 uint len, const u8 *buf, bool *stop)
+{
+	int ret;
+
+	ret = send_byte(dev, I2C_DTRM_STA | I2C_DTRM_NACK | addr << 1, stop);
+	if (ret < 0)
+		goto fail;
+
+	while (len--) {
+		ret = send_byte(dev, I2C_DTRM_NACK | *buf++, stop);
+		if (ret < 0)
+			goto fail;
+	}
+
+fail:
+	if (*stop)
+		writel(I2C_DTRM_STO | I2C_DTRM_NACK, dev->base + I2C_DTRM);
+
+	return ret;
+}
+
+static int uniphier_i2c_receive(struct uniphier_i2c_dev *dev, uint addr,
+				uint len, u8 *buf, bool *stop)
+{
+	int ret;
+
+	ret = send_byte(dev, I2C_DTRM_STA | I2C_DTRM_NACK |
+			I2C_DTRM_RD | addr << 1, stop);
+	if (ret < 0)
+		goto fail;
+
+	while (len--)
+		*buf++ = send_and_recv_byte(dev, len ? 0 : I2C_DTRM_NACK);
+
+fail:
+	if (*stop)
+		writel(I2C_DTRM_STO | I2C_DTRM_NACK, dev->base + I2C_DTRM);
+
+	return ret;
+}
+
+static int uniphier_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
+			     int nmsgs)
+{
+	int ret = 0;
+	struct uniphier_i2c_dev *dev = dev_get_priv(bus);
+	bool stop;
+
+	for (; nmsgs > 0; nmsgs--, msg++) {
+		/* If next message is read, skip the stop condition */
+		stop = nmsgs > 1 && msg[1].flags & I2C_M_RD ? false : true;
+
+		if (msg->flags & I2C_M_RD)
+			ret = uniphier_i2c_receive(dev, msg->addr, msg->len,
+						   msg->buf, &stop);
+		else
+			ret = uniphier_i2c_transmit(dev, msg->addr, msg->len,
+						    msg->buf, &stop);
+
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+
+static int uniphier_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
+{
+	struct uniphier_i2c_dev *priv = dev_get_priv(bus);
+
+	/* max supported frequency is 400 kHz */
+	if (speed > 400000)
+		return -EINVAL;
+
+	/* bus reset: make sure the bus is idle when change the frequency */
+	writel(0x1, priv->base + I2C_BRST);
+
+	writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed),
+	       priv->base + I2C_CLK);
+
+	writel(0x3, priv->base + I2C_BRST);
+
+	/*
+	 * Theoretically, each byte can be transferred in
+	 * 1000000 * 9 / speed usec.  For safety, wait more than double.
+	 */
+	priv->wait_us = 20000000 / speed;
+
+	return 0;
+}
+
+
+static const struct dm_i2c_ops uniphier_i2c_ops = {
+	.xfer = uniphier_i2c_xfer,
+	.set_bus_speed = uniphier_i2c_set_bus_speed,
+};
+
+static const struct udevice_id uniphier_i2c_of_match[] = {
+	{ .compatible = "panasonic,uniphier-i2c" },
+	{},
+};
+
+U_BOOT_DRIVER(uniphier_i2c) = {
+	.name = "uniphier-i2c",
+	.id = UCLASS_I2C,
+	.of_match = uniphier_i2c_of_match,
+	.probe = uniphier_i2c_probe,
+	.remove = uniphier_i2c_remove,
+	.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
+	.child_pre_probe = uniphier_i2c_child_pre_probe,
+	.priv_auto_alloc_size = sizeof(struct uniphier_i2c_dev),
+	.ops = &uniphier_i2c_ops,
+};
-- 
1.9.1