MIPS: I2C: Add driver for Cavium OCTEON I2C ports.

Signed-off-by: Rade Bozic <rade.bozic.ext@nsn.com>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: Michael Lawnick <michael.lawnick.ext@nsn.com>
To: linux-mips@linux-mips.org
To: linux-i2c@vger.kernel.org
To: ben-linux@fluff.org
To: khali@linux-fr.org
Cc: rade.bozic.ext@nsn.com
Cc: Michael Lawnick <michael.lawnick.ext@nsn.com>
Patchwork: http://patchwork.linux-mips.org/patch/890/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 651 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-octeon.c b/drivers/i2c/busses/i2c-octeon.c
new file mode 100644
index 00000000000..60375504fa4
--- /dev/null
+++ b/drivers/i2c/busses/i2c-octeon.c
@@ -0,0 +1,651 @@
+/*
+ * (C) Copyright 2009-2010
+ * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
+ *
+ * Portions Copyright (C) 2010 Cavium Networks, Inc.
+ *
+ * This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+
+#include <linux/io.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+
+#include <asm/octeon/octeon.h>
+
+#define DRV_NAME "i2c-octeon"
+
+/* The previous out-of-tree version was implicitly version 1.0. */
+#define DRV_VERSION	"2.0"
+
+/* register offsets */
+#define SW_TWSI	 0x00
+#define TWSI_INT 0x10
+
+/* Controller command patterns */
+#define SW_TWSI_V               0x8000000000000000ull
+#define SW_TWSI_EOP_TWSI_DATA   0x0C00000100000000ull
+#define SW_TWSI_EOP_TWSI_CTL    0x0C00000200000000ull
+#define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
+#define SW_TWSI_EOP_TWSI_STAT   0x0C00000300000000ull
+#define SW_TWSI_EOP_TWSI_RST    0x0C00000700000000ull
+#define SW_TWSI_OP_TWSI_CLK     0x0800000000000000ull
+#define SW_TWSI_R               0x0100000000000000ull
+
+/* Controller command and status bits */
+#define TWSI_CTL_CE   0x80
+#define TWSI_CTL_ENAB 0x40
+#define TWSI_CTL_STA  0x20
+#define TWSI_CTL_STP  0x10
+#define TWSI_CTL_IFLG 0x08
+#define TWSI_CTL_AAK  0x04
+
+/* Some status values */
+#define STAT_START      0x08
+#define STAT_RSTART     0x10
+#define STAT_TXADDR_ACK 0x18
+#define STAT_TXDATA_ACK 0x28
+#define STAT_RXADDR_ACK 0x40
+#define STAT_RXDATA_ACK 0x50
+#define STAT_IDLE       0xF8
+
+struct octeon_i2c {
+	wait_queue_head_t queue;
+	struct i2c_adapter adap;
+	int irq;
+	int twsi_freq;
+	int sys_freq;
+	resource_size_t twsi_phys;
+	void __iomem *twsi_base;
+	resource_size_t regsize;
+	struct device *dev;
+};
+
+/**
+ * octeon_i2c_write_sw - write an I2C core register.
+ * @i2c: The struct octeon_i2c.
+ * @eop_reg: Register selector.
+ * @data: Value to be written.
+ *
+ * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
+ */
+static void octeon_i2c_write_sw(struct octeon_i2c *i2c,
+				u64 eop_reg,
+				u8 data)
+{
+	u64 tmp;
+
+	__raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI);
+	do {
+		tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
+	} while ((tmp & SW_TWSI_V) != 0);
+}
+
+/**
+ * octeon_i2c_read_sw - write an I2C core register.
+ * @i2c: The struct octeon_i2c.
+ * @eop_reg: Register selector.
+ *
+ * Returns the data.
+ *
+ * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
+ */
+static u8 octeon_i2c_read_sw(struct octeon_i2c *i2c, u64 eop_reg)
+{
+	u64 tmp;
+
+	__raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI);
+	do {
+		tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
+	} while ((tmp & SW_TWSI_V) != 0);
+
+	return tmp & 0xFF;
+}
+
+/**
+ * octeon_i2c_write_int - write the TWSI_INT register
+ * @i2c: The struct octeon_i2c.
+ * @data: Value to be written.
+ */
+static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
+{
+	u64 tmp;
+
+	__raw_writeq(data, i2c->twsi_base + TWSI_INT);
+	tmp = __raw_readq(i2c->twsi_base + TWSI_INT);
+}
+
+/**
+ * octeon_i2c_int_enable - enable the TS interrupt.
+ * @i2c: The struct octeon_i2c.
+ *
+ * The interrupt will be asserted when there is non-STAT_IDLE state in
+ * the SW_TWSI_EOP_TWSI_STAT register.
+ */
+static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
+{
+	octeon_i2c_write_int(i2c, 0x40);
+}
+
+/**
+ * octeon_i2c_int_disable - disable the TS interrupt.
+ * @i2c: The struct octeon_i2c.
+ */
+static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
+{
+	octeon_i2c_write_int(i2c, 0);
+}
+
+/**
+ * octeon_i2c_unblock - unblock the bus.
+ * @i2c: The struct octeon_i2c.
+ *
+ * If there was a reset while a device was driving 0 to bus,
+ * bus is blocked. We toggle it free manually by some clock
+ * cycles and send a stop.
+ */
+static void octeon_i2c_unblock(struct octeon_i2c *i2c)
+{
+	int i;
+
+	dev_dbg(i2c->dev, "%s\n", __func__);
+	for (i = 0; i < 9; i++) {
+		octeon_i2c_write_int(i2c, 0x0);
+		udelay(5);
+		octeon_i2c_write_int(i2c, 0x200);
+		udelay(5);
+	}
+	octeon_i2c_write_int(i2c, 0x300);
+	udelay(5);
+	octeon_i2c_write_int(i2c, 0x100);
+	udelay(5);
+	octeon_i2c_write_int(i2c, 0x0);
+}
+
+/**
+ * octeon_i2c_isr - the interrupt service routine.
+ * @int: The irq, unused.
+ * @dev_id: Our struct octeon_i2c.
+ */
+static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
+{
+	struct octeon_i2c *i2c = dev_id;
+
+	octeon_i2c_int_disable(i2c);
+	wake_up_interruptible(&i2c->queue);
+
+	return IRQ_HANDLED;
+}
+
+
+static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
+{
+	return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0;
+}
+
+/**
+ * octeon_i2c_wait - wait for the IFLG to be set.
+ * @i2c: The struct octeon_i2c.
+ *
+ * Returns 0 on success, otherwise a negative errno.
+ */
+static int octeon_i2c_wait(struct octeon_i2c *i2c)
+{
+	int result;
+
+	octeon_i2c_int_enable(i2c);
+
+	result = wait_event_interruptible_timeout(i2c->queue,
+						  octeon_i2c_test_iflg(i2c),
+						  i2c->adap.timeout);
+
+	octeon_i2c_int_disable(i2c);
+
+	if (result < 0) {
+		dev_dbg(i2c->dev, "%s: wait interrupted\n", __func__);
+		return result;
+	} else if (result == 0) {
+		dev_dbg(i2c->dev, "%s: timeout\n", __func__);
+		result = -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/**
+ * octeon_i2c_start - send START to the bus.
+ * @i2c: The struct octeon_i2c.
+ *
+ * Returns 0 on success, otherwise a negative errno.
+ */
+static int octeon_i2c_start(struct octeon_i2c *i2c)
+{
+	u8 data;
+	int result;
+
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
+				TWSI_CTL_ENAB | TWSI_CTL_STA);
+
+	result = octeon_i2c_wait(i2c);
+	if (result) {
+		if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) {
+			/*
+			 * Controller refused to send start flag May
+			 * be a client is holding SDA low - let's try
+			 * to free it.
+			 */
+			octeon_i2c_unblock(i2c);
+			octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
+					    TWSI_CTL_ENAB | TWSI_CTL_STA);
+
+			result = octeon_i2c_wait(i2c);
+		}
+		if (result)
+			return result;
+	}
+
+	data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+	if ((data != STAT_START) && (data != STAT_RSTART)) {
+		dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * octeon_i2c_stop - send STOP to the bus.
+ * @i2c: The struct octeon_i2c.
+ *
+ * Returns 0 on success, otherwise a negative errno.
+ */
+static int octeon_i2c_stop(struct octeon_i2c *i2c)
+{
+	u8 data;
+
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
+			    TWSI_CTL_ENAB | TWSI_CTL_STP);
+
+	data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+
+	if (data != STAT_IDLE) {
+		dev_err(i2c->dev, "%s: bad status(0x%x)\n", __func__, data);
+		return -EIO;
+	}
+	return 0;
+}
+
+/**
+ * octeon_i2c_write - send data to the bus.
+ * @i2c: The struct octeon_i2c.
+ * @target: Target address.
+ * @data: Pointer to the data to be sent.
+ * @length: Length of the data.
+ *
+ * The address is sent over the bus, then the data.
+ *
+ * Returns 0 on success, otherwise a negative errno.
+ */
+static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
+			    const u8 *data, int length)
+{
+	int i, result;
+	u8 tmp;
+
+	result = octeon_i2c_start(i2c);
+	if (result)
+		return result;
+
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, target << 1);
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
+
+	result = octeon_i2c_wait(i2c);
+	if (result)
+		return result;
+
+	for (i = 0; i < length; i++) {
+		tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+		if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
+			dev_err(i2c->dev,
+				"%s: bad status before write (0x%x)\n",
+				__func__, tmp);
+			return -EIO;
+		}
+
+		octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]);
+		octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
+
+		result = octeon_i2c_wait(i2c);
+		if (result)
+			return result;
+	}
+
+	return 0;
+}
+
+/**
+ * octeon_i2c_read - receive data from the bus.
+ * @i2c: The struct octeon_i2c.
+ * @target: Target address.
+ * @data: Pointer to the location to store the datae .
+ * @length: Length of the data.
+ *
+ * The address is sent over the bus, then the data is read.
+ *
+ * Returns 0 on success, otherwise a negative errno.
+ */
+static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
+			   u8 *data, int length)
+{
+	int i, result;
+	u8 tmp;
+
+	if (length < 1)
+		return -EINVAL;
+
+	result = octeon_i2c_start(i2c);
+	if (result)
+		return result;
+
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target<<1) | 1);
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
+
+	result = octeon_i2c_wait(i2c);
+	if (result)
+		return result;
+
+	for (i = 0; i < length; i++) {
+		tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+		if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
+			dev_err(i2c->dev,
+				"%s: bad status before read (0x%x)\n",
+				__func__, tmp);
+			return -EIO;
+		}
+
+		if (i+1 < length)
+			octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
+						TWSI_CTL_ENAB | TWSI_CTL_AAK);
+		else
+			octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
+						TWSI_CTL_ENAB);
+
+		result = octeon_i2c_wait(i2c);
+		if (result)
+			return result;
+
+		data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
+	}
+	return 0;
+}
+
+/**
+ * octeon_i2c_xfer - The driver's master_xfer function.
+ * @adap: Pointer to the i2c_adapter structure.
+ * @msgs: Pointer to the messages to be processed.
+ * @num: Length of the MSGS array.
+ *
+ * Returns the number of messages processed, or a negative errno on
+ * failure.
+ */
+static int octeon_i2c_xfer(struct i2c_adapter *adap,
+			   struct i2c_msg *msgs,
+			   int num)
+{
+	struct i2c_msg *pmsg;
+	int i;
+	int ret = 0;
+	struct octeon_i2c *i2c = i2c_get_adapdata(adap);
+
+	for (i = 0; ret == 0 && i < num; i++) {
+		pmsg = &msgs[i];
+		dev_dbg(i2c->dev,
+			"Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
+			 pmsg->flags & I2C_M_RD ? "read" : "write",
+			 pmsg->len, pmsg->addr, i + 1, num);
+		if (pmsg->flags & I2C_M_RD)
+			ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
+						pmsg->len);
+		else
+			ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
+						pmsg->len);
+	}
+	octeon_i2c_stop(i2c);
+
+	return (ret != 0) ? ret : num;
+}
+
+static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm octeon_i2c_algo = {
+	.master_xfer = octeon_i2c_xfer,
+	.functionality = octeon_i2c_functionality,
+};
+
+static struct i2c_adapter octeon_i2c_ops = {
+	.owner = THIS_MODULE,
+	.name = "OCTEON adapter",
+	.algo = &octeon_i2c_algo,
+	.timeout = 2,
+};
+
+/**
+ * octeon_i2c_setclock - Calculate and set clock divisors.
+ */
+static int __init octeon_i2c_setclock(struct octeon_i2c *i2c)
+{
+	int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
+	int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
+
+	for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
+		/*
+		 * An mdiv value of less than 2 seems to not work well
+		 * with ds1337 RTCs, so we constrain it to larger
+		 * values.
+		 */
+		for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
+			/*
+			 * For given ndiv and mdiv values check the
+			 * two closest thp values.
+			 */
+			tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
+			tclk *= (1 << ndiv_idx);
+			thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
+			for (inc = 0; inc <= 1; inc++) {
+				thp_idx = thp_base + inc;
+				if (thp_idx < 5 || thp_idx > 0xff)
+					continue;
+
+				foscl = i2c->sys_freq / (2 * (thp_idx + 1));
+				foscl = foscl / (1 << ndiv_idx);
+				foscl = foscl / (mdiv_idx + 1) / 10;
+				diff = abs(foscl - i2c->twsi_freq);
+				if (diff < delta_hz) {
+					delta_hz = diff;
+					thp = thp_idx;
+					mdiv = mdiv_idx;
+					ndiv = ndiv_idx;
+				}
+			}
+		}
+	}
+	octeon_i2c_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
+
+	return 0;
+}
+
+static int __init octeon_i2c_initlowlevel(struct octeon_i2c *i2c)
+{
+	u8 status;
+	int tries;
+
+	/* disable high level controller, enable bus access */
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
+
+	/* reset controller */
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_RST, 0);
+
+	for (tries = 10; tries; tries--) {
+		udelay(1);
+		status = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+		if (status == STAT_IDLE)
+			return 0;
+	}
+	dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n", __func__, status);
+	return -EIO;
+}
+
+static int __devinit octeon_i2c_probe(struct platform_device *pdev)
+{
+	int irq, result = 0;
+	struct octeon_i2c *i2c;
+	struct octeon_i2c_data *i2c_data;
+	struct resource *res_mem;
+
+	/* All adaptors have an irq.  */
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
+	if (!i2c) {
+		dev_err(&pdev->dev, "kzalloc failed\n");
+		result = -ENOMEM;
+		goto out;
+	}
+	i2c->dev = &pdev->dev;
+	i2c_data = pdev->dev.platform_data;
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (res_mem == NULL) {
+		dev_err(i2c->dev, "found no memory resource\n");
+		result = -ENXIO;
+		goto fail_region;
+	}
+
+	if (i2c_data == NULL) {
+		dev_err(i2c->dev, "no I2C frequency data\n");
+		result = -ENXIO;
+		goto fail_region;
+	}
+
+	i2c->twsi_phys = res_mem->start;
+	i2c->regsize = resource_size(res_mem);
+	i2c->twsi_freq = i2c_data->i2c_freq;
+	i2c->sys_freq = i2c_data->sys_freq;
+
+	if (!request_mem_region(i2c->twsi_phys, i2c->regsize, res_mem->name)) {
+		dev_err(i2c->dev, "request_mem_region failed\n");
+		goto fail_region;
+	}
+	i2c->twsi_base = ioremap(i2c->twsi_phys, i2c->regsize);
+
+	init_waitqueue_head(&i2c->queue);
+
+	i2c->irq = irq;
+
+	result = request_irq(i2c->irq, octeon_i2c_isr, 0, DRV_NAME, i2c);
+	if (result < 0) {
+		dev_err(i2c->dev, "failed to attach interrupt\n");
+		goto fail_irq;
+	}
+
+	result = octeon_i2c_initlowlevel(i2c);
+	if (result) {
+		dev_err(i2c->dev, "init low level failed\n");
+		goto  fail_add;
+	}
+
+	result = octeon_i2c_setclock(i2c);
+	if (result) {
+		dev_err(i2c->dev, "clock init failed\n");
+		goto  fail_add;
+	}
+
+	i2c->adap = octeon_i2c_ops;
+	i2c->adap.dev.parent = &pdev->dev;
+	i2c->adap.nr = pdev->id >= 0 ? pdev->id : 0;
+	i2c_set_adapdata(&i2c->adap, i2c);
+	platform_set_drvdata(pdev, i2c);
+
+	result = i2c_add_numbered_adapter(&i2c->adap);
+	if (result < 0) {
+		dev_err(i2c->dev, "failed to add adapter\n");
+		goto fail_add;
+	}
+
+	dev_info(i2c->dev, "version %s\n", DRV_VERSION);
+
+	return result;
+
+fail_add:
+	platform_set_drvdata(pdev, NULL);
+	free_irq(i2c->irq, i2c);
+fail_irq:
+	iounmap(i2c->twsi_base);
+	release_mem_region(i2c->twsi_phys, i2c->regsize);
+fail_region:
+	kfree(i2c);
+out:
+	return result;
+};
+
+static int __devexit octeon_i2c_remove(struct platform_device *pdev)
+{
+	struct octeon_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	platform_set_drvdata(pdev, NULL);
+	free_irq(i2c->irq, i2c);
+	iounmap(i2c->twsi_base);
+	release_mem_region(i2c->twsi_phys, i2c->regsize);
+	kfree(i2c);
+	return 0;
+};
+
+static struct platform_driver octeon_i2c_driver = {
+	.probe		= octeon_i2c_probe,
+	.remove		= __devexit_p(octeon_i2c_remove),
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= DRV_NAME,
+	},
+};
+
+static int __init octeon_i2c_init(void)
+{
+	int rv;
+
+	rv = platform_driver_register(&octeon_i2c_driver);
+	return rv;
+}
+
+static void __exit octeon_i2c_exit(void)
+{
+	platform_driver_unregister(&octeon_i2c_driver);
+}
+
+MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
+MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+MODULE_ALIAS("platform:" DRV_NAME);
+
+module_init(octeon_i2c_init);
+module_exit(octeon_i2c_exit);