i2c: add driver for Freescale i.MX28

Currently only supporting the PIOQUEUE-mode, because DMA-support for
this platform is not yet in mainline. When it becomes available and
support has been added to this driver, it will also be suitable for
i.MX23 and STMP3xxx.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

drivers/i2c/busses/Kconfig

@@ -452,6 +452,16 @@ config I2C_MV64XXX
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-mv64xxx.
 
+config I2C_MXS
+	tristate "Freescale i.MX28 I2C interface"
+	depends on SOC_IMX28
+	help
+	  Say Y here if you want to use the I2C bus controller on
+	  the Freescale i.MX28 processors.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mxs.
+
 config I2C_NOMADIK
 	tristate "ST-Ericsson Nomadik/Ux500 I2C Controller"
 	depends on PLAT_NOMADIK

drivers/i2c/busses/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_IXP2000)	+= i2c-ixp2000.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
 obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
+obj-$(CONFIG_I2C_MXS)		+= i2c-mxs.o
 obj-$(CONFIG_I2C_NOMADIK)	+= i2c-nomadik.o
 obj-$(CONFIG_I2C_NUC900)	+= i2c-nuc900.o
 obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o

drivers/i2c/busses/i2c-mxs.c

+/*
+ * Freescale MXS I2C bus driver
+ *
+ * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
+ *
+ * based on a (non-working) driver which was:
+ *
+ * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * TODO: add dma-support if platform-support for it is available
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/platform_device.h>
+#include <linux/jiffies.h>
+#include <linux/io.h>
+
+#include <mach/common.h>
+
+#define DRIVER_NAME "mxs-i2c"
+
+#define MXS_I2C_CTRL0		(0x00)
+#define MXS_I2C_CTRL0_SET	(0x04)
+
+#define MXS_I2C_CTRL0_SFTRST			0x80000000
+#define MXS_I2C_CTRL0_SEND_NAK_ON_LAST		0x02000000
+#define MXS_I2C_CTRL0_RETAIN_CLOCK		0x00200000
+#define MXS_I2C_CTRL0_POST_SEND_STOP		0x00100000
+#define MXS_I2C_CTRL0_PRE_SEND_START		0x00080000
+#define MXS_I2C_CTRL0_MASTER_MODE		0x00020000
+#define MXS_I2C_CTRL0_DIRECTION			0x00010000
+#define MXS_I2C_CTRL0_XFER_COUNT(v)		((v) & 0x0000FFFF)
+
+#define MXS_I2C_CTRL1		(0x40)
+#define MXS_I2C_CTRL1_SET	(0x44)
+#define MXS_I2C_CTRL1_CLR	(0x48)
+
+#define MXS_I2C_CTRL1_BUS_FREE_IRQ		0x80
+#define MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ	0x40
+#define MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ		0x20
+#define MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ	0x10
+#define MXS_I2C_CTRL1_EARLY_TERM_IRQ		0x08
+#define MXS_I2C_CTRL1_MASTER_LOSS_IRQ		0x04
+#define MXS_I2C_CTRL1_SLAVE_STOP_IRQ		0x02
+#define MXS_I2C_CTRL1_SLAVE_IRQ			0x01
+
+#define MXS_I2C_IRQ_MASK	(MXS_I2C_CTRL1_DATA_ENGINE_CMPLT_IRQ | \
+				 MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ | \
+				 MXS_I2C_CTRL1_EARLY_TERM_IRQ | \
+				 MXS_I2C_CTRL1_MASTER_LOSS_IRQ | \
+				 MXS_I2C_CTRL1_SLAVE_STOP_IRQ | \
+				 MXS_I2C_CTRL1_SLAVE_IRQ)
+
+#define MXS_I2C_QUEUECTRL	(0x60)
+#define MXS_I2C_QUEUECTRL_SET	(0x64)
+#define MXS_I2C_QUEUECTRL_CLR	(0x68)
+
+#define MXS_I2C_QUEUECTRL_QUEUE_RUN		0x20
+#define MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE	0x04
+
+#define MXS_I2C_QUEUESTAT	(0x70)
+#define MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY        0x00002000
+
+#define MXS_I2C_QUEUECMD	(0x80)
+
+#define MXS_I2C_QUEUEDATA	(0x90)
+
+#define MXS_I2C_DATA		(0xa0)
+
+
+#define MXS_CMD_I2C_SELECT	(MXS_I2C_CTRL0_RETAIN_CLOCK |	\
+				 MXS_I2C_CTRL0_PRE_SEND_START |	\
+				 MXS_I2C_CTRL0_MASTER_MODE |	\
+				 MXS_I2C_CTRL0_DIRECTION |	\
+				 MXS_I2C_CTRL0_XFER_COUNT(1))
+
+#define MXS_CMD_I2C_WRITE	(MXS_I2C_CTRL0_PRE_SEND_START |	\
+				 MXS_I2C_CTRL0_MASTER_MODE |	\
+				 MXS_I2C_CTRL0_DIRECTION)
+
+#define MXS_CMD_I2C_READ	(MXS_I2C_CTRL0_SEND_NAK_ON_LAST | \
+				 MXS_I2C_CTRL0_MASTER_MODE)
+
+/**
+ * struct mxs_i2c_dev - per device, private MXS-I2C data
+ *
+ * @dev: driver model device node
+ * @regs: IO registers pointer
+ * @cmd_complete: completion object for transaction wait
+ * @cmd_err: error code for last transaction
+ * @adapter: i2c subsystem adapter node
+ */
+struct mxs_i2c_dev {
+	struct device *dev;
+	void __iomem *regs;
+	struct completion cmd_complete;
+	u32 cmd_err;
+	struct i2c_adapter adapter;
+};
+
+/*
+ * TODO: check if calls to here are really needed. If not, we could get rid of
+ * mxs_reset_block and the mach-dependency. Needs an I2C analyzer, probably.
+ */
+static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
+{
+	mxs_reset_block(i2c->regs);
+	writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
+}
+
+static void mxs_i2c_pioq_setup_read(struct mxs_i2c_dev *i2c, u8 addr, int len,
+					int flags)
+{
+	u32 data;
+
+	writel(MXS_CMD_I2C_SELECT, i2c->regs + MXS_I2C_QUEUECMD);
+
+	data = (addr << 1) | I2C_SMBUS_READ;
+	writel(data, i2c->regs + MXS_I2C_DATA);
+
+	data = MXS_CMD_I2C_READ | MXS_I2C_CTRL0_XFER_COUNT(len) | flags;
+	writel(data, i2c->regs + MXS_I2C_QUEUECMD);
+}
+
+static void mxs_i2c_pioq_setup_write(struct mxs_i2c_dev *i2c,
+				    u8 addr, u8 *buf, int len, int flags)
+{
+	u32 data;
+	int i, shifts_left;
+
+	data = MXS_CMD_I2C_WRITE | MXS_I2C_CTRL0_XFER_COUNT(len + 1) | flags;
+	writel(data, i2c->regs + MXS_I2C_QUEUECMD);
+
+	/*
+	 * We have to copy the slave address (u8) and buffer (arbitrary number
+	 * of u8) into the data register (u32). To achieve that, the u8 are put
+	 * into the MSBs of 'data' which is then shifted for the next u8. When
+	 * apropriate, 'data' is written to MXS_I2C_DATA. So, the first u32
+	 * looks like this:
+	 *
+	 *  3          2          1          0
+	 * 10987654|32109876|54321098|76543210
+	 * --------+--------+--------+--------
+	 * buffer+2|buffer+1|buffer+0|slave_addr
+	 */
+
+	data = ((addr << 1) | I2C_SMBUS_WRITE) << 24;
+
+	for (i = 0; i < len; i++) {
+		data >>= 8;
+		data |= buf[i] << 24;
+		if ((i & 3) == 2)
+			writel(data, i2c->regs + MXS_I2C_DATA);
+	}
+
+	/* Write out the remaining bytes if any */
+	shifts_left = 24 - (i & 3) * 8;
+	if (shifts_left)
+		writel(data >> shifts_left, i2c->regs + MXS_I2C_DATA);
+}
+
+/*
+ * TODO: should be replaceable with a waitqueue and RD_QUEUE_IRQ (setting the
+ * rd_threshold to 1). Couldn't get this to work, though.
+ */
+static int mxs_i2c_wait_for_data(struct mxs_i2c_dev *i2c)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+	while (readl(i2c->regs + MXS_I2C_QUEUESTAT)
+			& MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY) {
+			if (time_after(jiffies, timeout))
+				return -ETIMEDOUT;
+			cond_resched();
+	}
+
+	return 0;
+}
+
+static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
+{
+	u32 data;
+	int i;
+
+	for (i = 0; i < len; i++) {
+		if ((i & 3) == 0) {
+			if (mxs_i2c_wait_for_data(i2c))
+				return -ETIMEDOUT;
+			data = readl(i2c->regs + MXS_I2C_QUEUEDATA);
+		}
+		buf[i] = data & 0xff;
+		data >>= 8;
+	}
+
+	return 0;
+}
+
+/*
+ * Low level master read/write transaction.
+ */
+static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
+				int stop)
+{
+	struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+	int ret;
+	int flags;
+
+	init_completion(&i2c->cmd_complete);
+
+	dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
+		msg->addr, msg->len, msg->flags, stop);
+
+	if (msg->len == 0)
+		return -EINVAL;
+
+	flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
+
+	if (msg->flags & I2C_M_RD)
+		mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags);
+	else
+		mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len,
+					flags);
+
+	writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
+			i2c->regs + MXS_I2C_QUEUECTRL_SET);
+
+	ret = wait_for_completion_timeout(&i2c->cmd_complete,
+						msecs_to_jiffies(1000));
+	if (ret == 0)
+		goto timeout;
+
+	if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
+		ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len);
+		if (ret)
+			goto timeout;
+	}
+
+	if (i2c->cmd_err == -ENXIO)
+		mxs_i2c_reset(i2c);
+
+	dev_dbg(i2c->dev, "Done with err=%d\n", i2c->cmd_err);
+
+	return i2c->cmd_err;
+
+timeout:
+	dev_dbg(i2c->dev, "Timeout!\n");
+	mxs_i2c_reset(i2c);
+	return -ETIMEDOUT;
+}
+
+static int mxs_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
+			int num)
+{
+	int i;
+	int err;
+
+	for (i = 0; i < num; i++) {
+		err = mxs_i2c_xfer_msg(adap, &msgs[i], i == (num - 1));
+		if (err)
+			return err;
+	}
+
+	return num;
+}
+
+static u32 mxs_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+}
+
+static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
+{
+	struct mxs_i2c_dev *i2c = dev_id;
+	u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
+
+	if (!stat)
+		return IRQ_NONE;
+
+	if (stat & MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
+		i2c->cmd_err = -ENXIO;
+	else if (stat & (MXS_I2C_CTRL1_EARLY_TERM_IRQ |
+		    MXS_I2C_CTRL1_MASTER_LOSS_IRQ |
+		    MXS_I2C_CTRL1_SLAVE_STOP_IRQ | MXS_I2C_CTRL1_SLAVE_IRQ))
+		/* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
+		i2c->cmd_err = -EIO;
+	else
+		i2c->cmd_err = 0;
+
+	complete(&i2c->cmd_complete);
+
+	writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
+	return IRQ_HANDLED;
+}
+
+static const struct i2c_algorithm mxs_i2c_algo = {
+	.master_xfer = mxs_i2c_xfer,
+	.functionality = mxs_i2c_func,
+};
+
+static int __devinit mxs_i2c_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mxs_i2c_dev *i2c;
+	struct i2c_adapter *adap;
+	struct resource *res;
+	resource_size_t res_size;
+	int err, irq;
+
+	i2c = devm_kzalloc(dev, sizeof(struct mxs_i2c_dev), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	res_size = resource_size(res);
+	if (!devm_request_mem_region(dev, res->start, res_size, res->name))
+		return -EBUSY;
+
+	i2c->regs = devm_ioremap_nocache(dev, res->start, res_size);
+	if (!i2c->regs)
+		return -EBUSY;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
+	if (err)
+		return err;
+
+	i2c->dev = dev;
+	platform_set_drvdata(pdev, i2c);
+
+	/* Do reset to enforce correct startup after pinmuxing */
+	mxs_i2c_reset(i2c);
+	writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
+			i2c->regs + MXS_I2C_QUEUECTRL_SET);
+
+	adap = &i2c->adapter;
+	strlcpy(adap->name, "MXS I2C adapter", sizeof(adap->name));
+	adap->owner = THIS_MODULE;
+	adap->algo = &mxs_i2c_algo;
+	adap->dev.parent = dev;
+	adap->nr = pdev->id;
+	i2c_set_adapdata(adap, i2c);
+	err = i2c_add_numbered_adapter(adap);
+	if (err) {
+		dev_err(dev, "Failed to add adapter (%d)\n", err);
+		writel(MXS_I2C_CTRL0_SFTRST,
+				i2c->regs + MXS_I2C_CTRL0_SET);
+		return err;
+	}
+
+	return 0;
+}
+
+static int __devexit mxs_i2c_remove(struct platform_device *pdev)
+{
+	struct mxs_i2c_dev *i2c = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = i2c_del_adapter(&i2c->adapter);
+	if (ret)
+		return -EBUSY;
+
+	writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
+			i2c->regs + MXS_I2C_QUEUECTRL_CLR);
+	writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static struct platform_driver mxs_i2c_driver = {
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .owner = THIS_MODULE,
+		   },
+	.remove = __devexit_p(mxs_i2c_remove),
+};
+
+static int __init mxs_i2c_init(void)
+{
+	return platform_driver_probe(&mxs_i2c_driver, mxs_i2c_probe);
+}
+subsys_initcall(mxs_i2c_init);
+
+static void __exit mxs_i2c_exit(void)
+{
+	platform_driver_unregister(&mxs_i2c_driver);
+}
+module_exit(mxs_i2c_exit);
+
+MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
+MODULE_DESCRIPTION("MXS I2C Bus Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRIVER_NAME);