From 4596818bca07e0928168970839e08875cf51b4cc Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Mon, 29 Apr 2013 14:40:43 +0200
Subject: [PATCH 26/33] i2c: MIPS: adds ralink I2C driver

Signed-off-by: John Crispin <blogic@openwrt.org>
---
 .../devicetree/bindings/i2c/i2c-ralink.txt         |   27 ++
 drivers/i2c/busses/Kconfig                         |    4 +
 drivers/i2c/busses/Makefile                        |    1 +
 drivers/i2c/busses/i2c-ralink.c                    |  274 ++++++++++++++++++++
 4 files changed, 306 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-ralink.txt
 create mode 100644 drivers/i2c/busses/i2c-ralink.c

--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-ralink.txt
@@ -0,0 +1,27 @@
+I2C for Ralink platforms
+
+Required properties :
+- compatible : Must be "link,rt3052-i2c"
+- reg: physical base address of the controller and length of memory mapped
+     region.
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties:
+- Child nodes conforming to i2c bus binding
+
+Example :
+
+palmbus@10000000 {
+	i2c@900 {
+		compatible = "link,rt3052-i2c";
+		reg = <0x900 0x100>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		hwmon@4b {
+			compatible = "national,lm92";
+			reg = <0x4b>;
+		};
+	};
+};
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -629,6 +629,10 @@ config I2C_PXA_SLAVE
 	  is necessary for systems where the PXA may be a target on the
 	  I2C bus.
 
+config I2C_RALINK
+	tristate "Ralink I2C Controller"
+	select OF_I2C
+
 config HAVE_S3C2410_I2C
 	bool
 	help
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_I2C_PNX)		+= i2c-pnx.o
 obj-$(CONFIG_I2C_PUV3)		+= i2c-puv3.o
 obj-$(CONFIG_I2C_PXA)		+= i2c-pxa.o
 obj-$(CONFIG_I2C_PXA_PCI)	+= i2c-pxa-pci.o
+obj-$(CONFIG_I2C_RALINK)	+= i2c-ralink.o
 obj-$(CONFIG_I2C_S3C2410)	+= i2c-s3c2410.o
 obj-$(CONFIG_I2C_S6000)		+= i2c-s6000.o
 obj-$(CONFIG_I2C_SH7760)	+= i2c-sh7760.o
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ralink.c
@@ -0,0 +1,274 @@
+/*
+ * drivers/i2c/busses/i2c-ralink.c
+ *
+ * Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/reset.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/of_i2c.h>
+#include <linux/err.h>
+
+#include <asm/mach-ralink/ralink_regs.h>
+
+#define REG_CONFIG_REG		0x00
+#define REG_CLKDIV_REG		0x04
+#define REG_DEVADDR_REG		0x08
+#define REG_ADDR_REG		0x0C
+#define REG_DATAOUT_REG		0x10
+#define REG_DATAIN_REG		0x14
+#define REG_STATUS_REG		0x18
+#define REG_STARTXFR_REG	0x1C
+#define REG_BYTECNT_REG		0x20
+
+#define I2C_STARTERR		BIT(4)
+#define I2C_ACKERR		BIT(3)
+#define I2C_DATARDY		BIT(2)
+#define I2C_SDOEMPTY		BIT(1)
+#define I2C_BUSY		BIT(0)
+
+#define I2C_DEVADLEN_7		(6 << 2)
+#define I2C_ADDRDIS		BIT(1)
+
+#define I2C_RETRY		0x400
+
+#define CLKDIV_VALUE		200 // clock rate is 40M, 40M / (200*2) = 100k (standard i2c bus rate).
+//#define CLKDIV_VALUE		50 // clock rate is 40M, 40M / (50*2) = 400k (fast i2c bus rate).
+
+#define READ_CMD		0x01
+#define WRITE_CMD		0x00
+#define READ_BLOCK              64
+
+static void __iomem *membase;
+static struct i2c_adapter *adapter;
+
+static void rt_i2c_w32(u32 val, unsigned reg)
+{
+	iowrite32(val, membase + reg);
+}
+
+static u32 rt_i2c_r32(unsigned reg)
+{
+	return ioread32(membase + reg);
+}
+
+static inline int rt_i2c_wait_rx_done(void)
+{
+	int retries = I2C_RETRY;
+
+	do {
+		if (!retries--)
+			break;
+	} while(!(rt_i2c_r32(REG_STATUS_REG) & I2C_DATARDY));
+
+	return (retries < 0);
+}
+
+static inline int rt_i2c_wait_idle(void)
+{
+	int retries = I2C_RETRY;
+
+	do {
+		if (!retries--)
+			break;
+	} while(rt_i2c_r32(REG_STATUS_REG) & I2C_BUSY);
+
+	return (retries < 0);
+}
+
+static inline int rt_i2c_wait_tx_done(void)
+{
+	int retries = I2C_RETRY;
+
+	do {
+		if (!retries--)
+			break;
+	} while(!(rt_i2c_r32(REG_STATUS_REG) & I2C_SDOEMPTY));
+
+	return (retries < 0);
+}
+
+static int rt_i2c_handle_msg(struct i2c_adapter *a, struct i2c_msg* msg)
+{
+	int i = 0, j = 0, pos = 0;
+	int nblock = msg->len / READ_BLOCK;
+        int rem = msg->len % READ_BLOCK;
+
+	if (msg->flags & I2C_M_TEN) {
+		printk("10 bits addr not supported\n");
+		return -EINVAL;
+	}
+
+	if (msg->flags & I2C_M_RD) {
+		for (i = 0; i < nblock; i++) {
+			rt_i2c_wait_idle();
+			rt_i2c_w32(READ_BLOCK - 1, REG_BYTECNT_REG);
+			rt_i2c_w32(READ_CMD, REG_STARTXFR_REG);
+			for (j = 0; j < READ_BLOCK; j++) {
+				if (rt_i2c_wait_rx_done())
+					return -1;
+				msg->buf[pos++] = rt_i2c_r32(REG_DATAIN_REG);
+			}
+		}
+
+		rt_i2c_wait_idle();
+		rt_i2c_w32(rem - 1, REG_BYTECNT_REG);
+		rt_i2c_w32(READ_CMD, REG_STARTXFR_REG);
+		for (i = 0; i < rem; i++) {
+			if (rt_i2c_wait_rx_done())
+				return -1;
+			msg->buf[pos++] = rt_i2c_r32(REG_DATAIN_REG);
+		}
+	} else {
+		rt_i2c_wait_idle();
+		rt_i2c_w32(msg->len - 1, REG_BYTECNT_REG);
+		for (i = 0; i < msg->len; i++) {
+			rt_i2c_w32(msg->buf[i], REG_DATAOUT_REG);
+			rt_i2c_w32(WRITE_CMD, REG_STARTXFR_REG);
+			if (rt_i2c_wait_tx_done())
+				return -1;
+		}
+	}
+
+	return 0;
+}
+
+static int rt_i2c_master_xfer(struct i2c_adapter *a, struct i2c_msg *m, int n)
+{
+	int i = 0;
+	int ret = 0;
+
+	if (rt_i2c_wait_idle()) {
+		printk("i2c transfer failed\n");
+		return 0;
+	}
+
+	device_reset(a->dev.parent);
+
+	rt_i2c_w32(m->addr, REG_DEVADDR_REG);
+	rt_i2c_w32(I2C_DEVADLEN_7 | I2C_ADDRDIS, REG_CONFIG_REG);
+	rt_i2c_w32(CLKDIV_VALUE, REG_CLKDIV_REG);
+
+	for (i = 0; i < n && !ret; i++)
+		ret = rt_i2c_handle_msg(a, &m[i]);
+
+	if (ret) {
+		printk("i2c transfer failed\n");
+		return 0;
+	}
+
+	return n;
+}
+
+static u32 rt_i2c_func(struct i2c_adapter *a)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm rt_i2c_algo = {
+	.master_xfer	= rt_i2c_master_xfer,
+	.functionality	= rt_i2c_func,
+};
+
+static int rt_i2c_probe(struct platform_device *pdev)
+{
+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	int ret;
+
+	if (!res) {
+		dev_err(&pdev->dev, "no memory resource found\n");
+		return -ENODEV;
+	}
+
+	adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
+	if (!adapter) {
+		dev_err(&pdev->dev, "failed to allocate i2c_adapter\n");
+		return -ENOMEM;
+	}
+
+	membase = devm_request_and_ioremap(&pdev->dev, res);
+	if (IS_ERR(membase))
+		return PTR_ERR(membase);
+
+	strlcpy(adapter->name, dev_name(&pdev->dev), sizeof(adapter->name));
+	adapter->owner = THIS_MODULE;
+	adapter->nr = pdev->id;
+	adapter->timeout = HZ;
+	adapter->algo = &rt_i2c_algo;
+	adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	adapter->dev.parent = &pdev->dev;
+	adapter->dev.of_node = pdev->dev.of_node;
+
+	ret = i2c_add_numbered_adapter(adapter);
+	if (ret)
+		return ret;
+
+	of_i2c_register_devices(adapter);
+
+	platform_set_drvdata(pdev, adapter);
+
+	dev_info(&pdev->dev, "loaded\n");
+
+	return 0;
+}
+
+static int rt_i2c_remove(struct platform_device *pdev)
+{
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id i2c_rt_dt_ids[] = {
+	{ .compatible = "ralink,rt2880-i2c", },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, i2c_rt_dt_ids);
+
+static struct platform_driver rt_i2c_driver = {
+	.probe		= rt_i2c_probe,
+	.remove		= rt_i2c_remove,
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "i2c-ralink",
+		.of_match_table = i2c_rt_dt_ids,
+	},
+};
+
+static int __init i2c_rt_init (void)
+{
+	return platform_driver_register(&rt_i2c_driver);
+}
+subsys_initcall(i2c_rt_init);
+
+static void __exit i2c_rt_exit (void)
+{
+	platform_driver_unregister(&rt_i2c_driver);
+}
+
+module_exit (i2c_rt_exit);
+
+MODULE_AUTHOR("Steven Liu <steven_liu@mediatek.com>");
+MODULE_DESCRIPTION("Ralink I2c host driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:Ralink-I2C");
