i2c: UniPhier: add driver for UniPhier i2c controller

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>
Acked-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

drivers/i2c/Kconfig

@@ -4,3 +4,11 @@ config DM_I2C
 	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.

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

drivers/i2c/i2c-uniphier.c

@@ -0,0 +1,239 @@
+/*
+ * 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;
+
+struct uniphier_i2c_regs {
+	u32 dtrm;			/* 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)
+	u32 drec;			/* data reception */
+#define I2C_DREC_STS	(1 << 12)
+#define I2C_DREC_LRB	(1 << 11)
+#define I2C_DREC_LAB	(1 << 9)
+	u32 myad;			/* slave address */
+	u32 clk;			/* clock frequency control */
+	u32 brst;			/* bus reset */
+#define I2C_BRST_FOEN	(1 << 1)
+#define I2C_BRST_BRST	(1 << 0)
+	u32 hold;			/* hold time control */
+	u32 bsts;			/* bus status monitor */
+	u32 noise;			/* noise filter control */
+	u32 setup;			/* setup time control */
+};
+
+#define IOBUS_FREQ	100000000
+
+struct uniphier_i2c_dev {
+	struct uniphier_i2c_regs __iomem *regs;	/* 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->regs = map_sysmem(addr, size);
+
+	if (!priv->regs)
+		return -ENOMEM;
+
+	priv->input_clk = IOBUS_FREQ;
+
+	/* deassert reset */
+	writel(0x3, &priv->regs->brst);
+
+	return 0;
+}
+
+static int uniphier_i2c_remove(struct udevice *dev)
+{
+	struct uniphier_i2c_dev *priv = dev_get_priv(dev);
+
+	unmap_sysmem(priv->regs);
+
+	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->regs->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->regs->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;
+
+	debug("%s: addr = %x, len = %d\n", __func__, addr, len);
+
+	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->regs->dtrm);
+
+	return ret;
+}
+
+static int uniphier_i2c_receive(struct uniphier_i2c_dev *dev, uint addr,
+				uint len, u8 *buf, bool *stop)
+{
+	int ret;
+
+	debug("%s: addr = %x, len = %d\n", __func__, addr, len);
+
+	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->regs->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->regs->brst);
+
+	writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed),
+	       &priv->regs->clk);
+
+	writel(0x3, &priv->regs->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,
+};