[RFC PATCH 2/5] i2c-dmec: add i2c bus support for dmec

[Zahari Doychev]

This is support for the i2c bus functionality of the Data Modul embedded
controllers.

Signed-off-by: Zahari Doychev <zahari.doychev@xxxxxxxxx>
---
 drivers/staging/dmec/Kconfig    |  10 +-
 drivers/staging/dmec/Makefile   |   1 +-
 drivers/staging/dmec/dmec.h     |   9 +-
 drivers/staging/dmec/i2c-dmec.c | 524 +++++++++++++++++++++++++++++++++-
 4 files changed, 544 insertions(+), 0 deletions(-)
 create mode 100644 drivers/staging/dmec/i2c-dmec.c

diff --git a/drivers/staging/dmec/Kconfig b/drivers/staging/dmec/Kconfig
index 3641907..0067b0b 100644
--- a/drivers/staging/dmec/Kconfig
+++ b/drivers/staging/dmec/Kconfig
@@ -7,3 +7,13 @@ config MFD_DMEC
 
 	    To compile this driver as a module, say M here: the module will be
             called dmec
+
+config I2C_DMEC
+	tristate "Data Modul I2C"
+	depends on MFD_DMEC && I2C
+	help
+	  Say Y here to enable support for a i2c bus on the Data Modul
+	  embedded controller.
+
+	  To compile this driver as a module, say M here: the module will be
+          called i2c-dmec
diff --git a/drivers/staging/dmec/Makefile b/drivers/staging/dmec/Makefile
index 859163b..c51a37e 100644
--- a/drivers/staging/dmec/Makefile
+++ b/drivers/staging/dmec/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_MFD_DMEC)		+= dmec-core.o
+obj-$(CONFIG_I2C_DMEC)		+= i2c-dmec.o
diff --git a/drivers/staging/dmec/dmec.h b/drivers/staging/dmec/dmec.h
index 4d8712d..178937d 100644
--- a/drivers/staging/dmec/dmec.h
+++ b/drivers/staging/dmec/dmec.h
@@ -1,6 +1,15 @@
 #ifndef _LINUX_MFD_DMEC_H
 #define _LINUX_MFD_DMEC_H
 
+struct dmec_i2c_platform_data {
+	u32 reg_shift; /* register offset shift value */
+	u32 reg_io_width; /* register io read/write width */
+	u32 clock_khz; /* input clock in kHz */
+	bool big_endian; /* registers are big endian */
+	u8 num_devices; /* number of devices in the devices list */
+	struct i2c_board_info const *devices; /* devices connected to the bus */
+};
+
 struct regmap *dmec_get_regmap(struct device *dev);
 
 #endif
diff --git a/drivers/staging/dmec/i2c-dmec.c b/drivers/staging/dmec/i2c-dmec.c
new file mode 100644
index 0000000..456e61e
--- /dev/null
+++ b/drivers/staging/dmec/i2c-dmec.c
@@ -0,0 +1,524 @@
+/*
+ * i2c-dmec.c: I2C bus driver for OpenCores I2C controller
+ * (http://www.opencores.org/projects.cgi/web/i2c/overview).
+ *
+ * Peter Korsgaard <jacmet@xxxxxxxxxx>
+ *
+ * Support for the GRLIB port of the controller by
+ * Andreas Larsson <andreas@xxxxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/wait.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/interrupt.h>
+#include "dmec.h"
+
+/* registers */
+#define DMECI2C_PRELOW		0
+#define DMECI2C_PREHIGH		1
+#define DMECI2C_CONTROL		2
+#define DMECI2C_DATA		3
+#define DMECI2C_CMD		4 /* write only */
+#define DMECI2C_STATUS		4 /* read only, same address as DMECI2C_CMD */
+#define DMECI2C_VER		5
+#define DMECI2C_MUX		6 /* i2c demultiplezer */
+
+#define DMECI2C_CTRL_EN		BIT(7)
+#define DMECI2C_CTRL_IEN	BIT(6)
+#define DMECI2C_CTRL_VSSCL	BIT(5)
+#define DMECI2C_CTRL_MABCLR	BIT(4)
+#define DMECI2C_CTRL_MMDIS	BIT(3)
+#define DMECI2C_CTRL_VSSDA	BIT(2)
+
+#define DMECI2C_CMD_START	0x91
+#define DMECI2C_CMD_STOP	0x41
+#define DMECI2C_CMD_READ	0x21
+#define DMECI2C_CMD_WRITE	0x11
+#define DMECI2C_CMD_READ_ACK	0x21
+#define DMECI2C_CMD_READ_NACK	0x29
+#define DMECI2C_CMD_IACK	0x01
+
+#define DMECI2C_STAT_IF		0x01
+#define DMECI2C_STAT_TIP	0x02
+#define DMECI2C_STAT_ARBLOST	0x20
+#define DMECI2C_STAT_BUSY	0x40
+#define DMECI2C_STAT_NACK	0x80
+
+#define STATE_DONE		0
+#define STATE_START		1
+#define STATE_WRITE		2
+#define STATE_READ		3
+#define STATE_ERROR		4
+
+#define TYPE_OCORES		0
+#define TYPE_GRLIB		1
+
+#define DMEC_I2C_OFFSET		0x20
+#define DMEC_I2C_MAX_BUS_NUM	3
+
+struct dmec_i2c {
+	struct device *dev;
+	void __iomem *base;
+	u32 reg_shift;
+	u32 reg_io_width;
+	wait_queue_head_t wait;
+	struct i2c_adapter adap;
+	struct i2c_mux_core *mux;
+	struct i2c_msg *msg;
+	int pos;
+	int nmsgs;
+	int state; /* see STATE_ */
+	struct clk *clk;
+	int ip_clock_khz;
+	int bus_clock_khz;
+
+	u8 irq;
+	struct regmap *regmap;
+};
+
+static int flags;
+module_param(flags, int, 0644);
+MODULE_PARM_DESC(flags, "additional flags for the i2c bus configuration");
+
+static inline void dmec_i2c_setreg(struct dmec_i2c *i2c, int reg, u8 value)
+{
+	struct regmap *regmap = i2c->regmap;
+
+	regmap_write(regmap, DMEC_I2C_OFFSET + reg, value);
+}
+
+static inline u8 dmec_i2c_getreg(struct dmec_i2c *i2c, int reg)
+{
+	struct regmap *regmap = i2c->regmap;
+	unsigned int val;
+
+	regmap_read(regmap, DMEC_I2C_OFFSET + reg, &val);
+
+	return val;
+}
+
+static int dmec_i2c_dmx_select(struct i2c_mux_core *mux, u32 chan)
+{
+	struct dmec_i2c *i2c = mux->priv;
+	u8 bus = chan & 0x3;
+
+	dmec_i2c_setreg(i2c, DMECI2C_MUX, bus);
+
+	return 0;
+}
+
+static void dmec_i2c_dmx_del(struct dmec_i2c *i2c)
+{
+	if (i2c->mux)
+		i2c_mux_del_adapters(i2c->mux);
+}
+
+static int dmec_i2c_dmx_add(struct dmec_i2c *i2c)
+{
+	u8 bus_mask;
+	int i, ret = 0;
+
+	bus_mask = dmec_i2c_getreg(i2c, DMECI2C_MUX);
+	bus_mask = (bus_mask & 0x70) >> 4;
+
+	i2c->mux = i2c_mux_alloc(&i2c->adap,
+				 i2c->dev,
+				 DMEC_I2C_MAX_BUS_NUM, 0, 0,
+				 dmec_i2c_dmx_select,
+				 NULL);
+	if (!i2c->mux)
+		return -ENOMEM;
+
+	i2c->mux->priv = i2c;
+
+	for (i = 0; i < DMEC_I2C_MAX_BUS_NUM; i++) {
+		if (!(bus_mask & (i + 1)))
+			/* bus is not present so skip */
+			continue;
+		ret = i2c_mux_add_adapter(i2c->mux, 0, i, 0);
+		if (ret) {
+			ret = -ENODEV;
+			dev_err(i2c->dev,
+				"i2c dmx failed to register adapter %d\n", i);
+			goto dmec_i2c_dmx_add_failed;
+		}
+	}
+
+	return 0;
+
+dmec_i2c_dmx_add_failed:
+	dmec_i2c_dmx_del(i2c);
+	return ret;
+}
+
+static void dmec_i2c_process(struct dmec_i2c *i2c)
+{
+	struct i2c_msg *msg = i2c->msg;
+	u8 stat = dmec_i2c_getreg(i2c, DMECI2C_STATUS);
+
+	if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
+		/* stop has been sent */
+		dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_IACK);
+		wake_up(&i2c->wait);
+		return;
+	}
+
+	/* error? */
+	if (stat & DMECI2C_STAT_ARBLOST) {
+		i2c->state = STATE_ERROR;
+		dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_STOP);
+		return;
+	}
+
+	if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) {
+		i2c->state =
+			(msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
+
+		if (stat & DMECI2C_STAT_NACK) {
+			i2c->state = STATE_ERROR;
+			dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_STOP);
+			return;
+		}
+	} else {
+		msg->buf[i2c->pos++] = dmec_i2c_getreg(i2c, DMECI2C_DATA);
+	}
+
+	/* end of msg? */
+	if (i2c->pos == msg->len) {
+		i2c->nmsgs--;
+		i2c->msg++;
+		i2c->pos = 0;
+		msg = i2c->msg;
+
+		if (i2c->nmsgs) {	/* end? */
+			/* send start? */
+			if (!(msg->flags & I2C_M_NOSTART)) {
+				u8 addr = (msg->addr << 1);
+
+				if (msg->flags & I2C_M_RD)
+					addr |= 1;
+
+				i2c->state = STATE_START;
+
+				dmec_i2c_setreg(i2c, DMECI2C_DATA, addr);
+				dmec_i2c_setreg(i2c, DMECI2C_CMD,
+						DMECI2C_CMD_START);
+				return;
+			}
+			i2c->state = (msg->flags & I2C_M_RD)
+					? STATE_READ : STATE_WRITE;
+		} else {
+			i2c->state = STATE_DONE;
+			dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_STOP);
+			return;
+		}
+	}
+
+	if (i2c->state == STATE_READ) {
+		dmec_i2c_setreg(i2c, DMECI2C_CMD, i2c->pos == (msg->len - 1) ?
+			  DMECI2C_CMD_READ_NACK : DMECI2C_CMD_READ_ACK);
+	} else {
+		dmec_i2c_setreg(i2c, DMECI2C_DATA, msg->buf[i2c->pos++]);
+		dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_WRITE);
+	}
+}
+
+static irqreturn_t dmec_i2c_isr(int irq, void *dev_id)
+{
+	struct dmec_i2c *i2c = dev_id;
+
+	dmec_i2c_process(i2c);
+
+	return IRQ_HANDLED;
+}
+
+static int dmec_i2c_xfer(struct i2c_adapter *adap,
+			 struct i2c_msg *msgs, int num)
+{
+	struct dmec_i2c *i2c = i2c_get_adapdata(adap);
+
+	i2c->msg = msgs;
+	i2c->pos = 0;
+	i2c->nmsgs = num;
+	i2c->state = STATE_START;
+
+	dmec_i2c_setreg(i2c, DMECI2C_DATA,
+			(i2c->msg->addr << 1) |
+			((i2c->msg->flags & I2C_M_RD) ? 1 : 0));
+
+	dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_START);
+
+	if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
+			       (i2c->state == STATE_DONE), HZ))
+		return (i2c->state == STATE_DONE) ? num : -EIO;
+	else
+		return -ETIMEDOUT;
+}
+
+static int dmec_i2c_init(struct device *dev, struct dmec_i2c *i2c)
+{
+	int prescale;
+	int diff;
+	u8 stat;
+	u8 ctrl = dmec_i2c_getreg(i2c, DMECI2C_CONTROL);
+
+	/* make sure the device is disabled */
+	ctrl &= ~(DMECI2C_CTRL_EN | DMECI2C_CTRL_IEN |
+		  DMECI2C_CTRL_VSSCL | DMECI2C_CTRL_VSSDA |
+		  DMECI2C_CTRL_MABCLR | DMECI2C_CTRL_MMDIS);
+	dmec_i2c_setreg(i2c, DMECI2C_CONTROL, ctrl);
+
+	prescale = (i2c->ip_clock_khz / (8 * i2c->bus_clock_khz)) - 2;
+	prescale = clamp(prescale, 0, 0xffff);
+
+	diff = i2c->ip_clock_khz / (8 * (prescale + 2)) - i2c->bus_clock_khz;
+	if (abs(diff) > i2c->bus_clock_khz / 10) {
+		dev_err(dev,
+			"Unsupported clock: core: %d KHz, bus: %d KHz\n",
+			i2c->ip_clock_khz, i2c->bus_clock_khz);
+		return -EINVAL;
+	}
+
+	dmec_i2c_setreg(i2c, DMECI2C_PRELOW, prescale & 0xff);
+	dmec_i2c_setreg(i2c, DMECI2C_PREHIGH, prescale >> 8);
+
+	/* default to first bus */
+	dmec_i2c_setreg(i2c, DMECI2C_MUX, 0x0);
+
+	/* Init the device */
+	dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_IACK);
+	ctrl |= DMECI2C_CTRL_EN;
+	if (!flags)
+		ctrl |= DMECI2C_CTRL_MABCLR | DMECI2C_CTRL_MMDIS;
+	else
+		ctrl |= (flags & 0x3c);
+	dmec_i2c_setreg(i2c, DMECI2C_CONTROL, ctrl);
+
+	stat = dmec_i2c_getreg(i2c, DMECI2C_STATUS);
+	if (stat & DMECI2C_STAT_BUSY) {
+		dev_warn(dev,
+			 "I2C bus is busy - generating stop signal\n");
+		dmec_i2c_setreg(i2c, DMECI2C_CMD, DMECI2C_CMD_STOP);
+	}
+
+	stat = dmec_i2c_getreg(i2c, DMECI2C_VER);
+	dev_info(dev, "v%u.%u\n", (stat >> 4) & 0xf, stat & 0xf);
+
+	return 0;
+}
+
+static int dmec_i2c_irq_enable(struct dmec_i2c *i2c)
+{
+	u8 ctrl;
+	unsigned int irq;
+	int ret;
+
+	irq = i2c->irq;
+
+	/* Initialize interrupt handlers if not already done */
+	init_waitqueue_head(&i2c->wait);
+
+	ret = devm_request_threaded_irq(i2c->dev, irq, NULL, dmec_i2c_isr,
+					IRQF_ONESHOT | IRQF_SHARED,
+					i2c->adap.name, i2c);
+	if (ret) {
+		dev_err(i2c->dev,
+			"Unable to claim IRQ\n");
+		return ret;
+	}
+
+	/* Now enable interrupts in the controller */
+	ctrl = dmec_i2c_getreg(i2c, DMECI2C_CONTROL);
+	ctrl |= DMECI2C_CTRL_IEN;
+	dmec_i2c_setreg(i2c, DMECI2C_CONTROL, ctrl);
+
+	return 0;
+}
+
+static int dmec_i2c_irq_disable(struct dmec_i2c *i2c)
+{
+	u8 ctrl;
+
+	ctrl = dmec_i2c_getreg(i2c, DMECI2C_CONTROL);
+	ctrl &= ~DMECI2C_CTRL_IEN;
+	dmec_i2c_setreg(i2c, DMECI2C_CONTROL, ctrl);
+
+	devm_free_irq(i2c->dev, i2c->irq, i2c);
+
+	return 0;
+}
+
+static u32 dmec_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm dmec_algorithm = {
+	.master_xfer = dmec_i2c_xfer,
+	.functionality = dmec_i2c_func,
+};
+
+static struct i2c_adapter dmec_adapter = {
+	.owner = THIS_MODULE,
+	.name = "i2c-dmec",
+	.class = I2C_CLASS_DEPRECATED,
+	.algo = &dmec_algorithm,
+};
+
+#define dmec_i2c_of_probe(pdev, i2c) -ENODEV
+
+static int dmec_i2c_probe(struct platform_device *pdev)
+{
+	struct dmec_i2c *i2c;
+	struct dmec_i2c_platform_data *pdata;
+	int ret;
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	i2c->dev = &pdev->dev;
+	pdata = dev_get_platdata(&pdev->dev);
+	if (pdata) {
+		i2c->reg_shift = pdata->reg_shift;
+		i2c->reg_io_width = pdata->reg_io_width;
+		i2c->ip_clock_khz = pdata->clock_khz;
+		i2c->bus_clock_khz = 100;
+		i2c->regmap = dmec_get_regmap(pdev->dev.parent);
+	} else {
+		ret = dmec_i2c_of_probe(pdev, i2c);
+		if (ret)
+			return ret;
+	}
+
+	if (i2c->reg_io_width == 0)
+		i2c->reg_io_width = 1; /* Set to default value */
+
+	i2c->irq = platform_get_irq(pdev, 0);
+
+	ret = dmec_i2c_init(&pdev->dev, i2c);
+	if (ret)
+		return ret;
+
+	/* hook up driver to tree */
+	platform_set_drvdata(pdev, i2c);
+	i2c->adap = dmec_adapter;
+	i2c_set_adapdata(&i2c->adap, i2c);
+	i2c->adap.dev.parent = &pdev->dev;
+	i2c->adap.dev.of_node = pdev->dev.of_node;
+
+	if (dmec_i2c_irq_enable(i2c)) {
+		dev_err(&pdev->dev, "Cannot claim IRQ\n");
+		return ret;
+	}
+
+	/* add i2c adapter to i2c tree */
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to add adapter\n");
+		return ret;
+	}
+
+	ret = dmec_i2c_dmx_add(i2c);
+
+	return ret;
+}
+
+static int dmec_i2c_remove(struct platform_device *pdev)
+{
+	struct dmec_i2c *i2c = platform_get_drvdata(pdev);
+
+	/* disable i2c logic */
+	dmec_i2c_setreg(i2c, DMECI2C_CONTROL,
+			dmec_i2c_getreg(i2c, DMECI2C_CONTROL)
+			& ~(DMECI2C_CTRL_EN | DMECI2C_CTRL_IEN));
+
+	/* remove adapter & data */
+	dmec_i2c_dmx_del(i2c);
+	i2c_del_adapter(&i2c->adap);
+
+	if (!IS_ERR(i2c->clk))
+		clk_disable_unprepare(i2c->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int dmec_i2c_suspend(struct device *dev)
+{
+	struct dmec_i2c *i2c = dev_get_drvdata(dev);
+	u8 ctrl = dmec_i2c_getreg(i2c, DMECI2C_CONTROL);
+
+	dmec_i2c_irq_disable(i2c);
+
+	/* make sure the device is disabled */
+	dmec_i2c_setreg(i2c, DMECI2C_CONTROL,
+			ctrl & ~DMECI2C_CTRL_EN);
+
+	if (!IS_ERR(i2c->clk))
+		clk_disable_unprepare(i2c->clk);
+	return 0;
+}
+
+static int dmec_i2c_resume(struct device *dev)
+{
+	struct dmec_i2c *i2c = dev_get_drvdata(dev);
+	int ret;
+
+	if (!IS_ERR(i2c->clk)) {
+		unsigned long rate;
+
+		ret = clk_prepare_enable(i2c->clk);
+
+		if (ret) {
+			dev_err(dev,
+				"clk_prepare_enable failed: %d\n", ret);
+			return ret;
+		}
+		rate = clk_get_rate(i2c->clk) / 1000;
+		if (rate)
+			i2c->ip_clock_khz = rate;
+	}
+
+	ret = dmec_i2c_init(dev, i2c);
+	if (ret)
+		return ret;
+	return dmec_i2c_irq_enable(i2c);
+}
+
+static SIMPLE_DEV_PM_OPS(dmec_i2c_pm, dmec_i2c_suspend, dmec_i2c_resume);
+#define DMEC_I2C_PM	(&dmec_i2c_pm)
+#else
+#define DMEC_I2C_PM	NULL
+#endif
+
+static struct platform_driver dmec_i2c_driver = {
+	.probe   = dmec_i2c_probe,
+	.remove  = dmec_i2c_remove,
+	.driver  = {
+		.name = "dmec-i2c",
+		.pm = DMEC_I2C_PM,
+	},
+};
+
+module_platform_driver(dmec_i2c_driver);
+
+MODULE_AUTHOR("Peter Korsgaard <jacmet@xxxxxxxxxx>");
+MODULE_AUTHOR("Zahari Doychev <zahari.doychev@xxxxxxxxx>");
+MODULE_DESCRIPTION("DMO OpenCores based I2C bus driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:dmec-i2c");
-- 
git-series 0.8.10