1 files changed, 512 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-bcm2708.c b/drivers/i2c/busses/i2c-bcm2708.c
new file mode 100644
index 000000000000..962f2e5c7455
--- /dev/null
+++ b/drivers/i2c/busses/i2c-bcm2708.c
@@ -0,0 +1,512 @@
+/*
+ * Driver for Broadcom BCM2708 BSC Controllers
+ *
+ * Copyright (C) 2012 Chris Boot & Frank Buss
+ *
+ * This driver is inspired by:
+ * i2c-ocores.c, by Peter Korsgaard <jacmet@sunsite.dk>
+ *
+ * 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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+
+/* BSC register offsets */
+#define BSC_C			0x00
+#define BSC_S			0x04
+#define BSC_DLEN		0x08
+#define BSC_A			0x0c
+#define BSC_FIFO		0x10
+#define BSC_DIV			0x14
+#define BSC_DEL			0x18
+#define BSC_CLKT		0x1c
+
+/* Bitfields in BSC_C */
+#define BSC_C_I2CEN		0x00008000
+#define BSC_C_INTR		0x00000400
+#define BSC_C_INTT		0x00000200
+#define BSC_C_INTD		0x00000100
+#define BSC_C_ST		0x00000080
+#define BSC_C_CLEAR_1		0x00000020
+#define BSC_C_CLEAR_2		0x00000010
+#define BSC_C_READ		0x00000001
+
+/* Bitfields in BSC_S */
+#define BSC_S_CLKT		0x00000200
+#define BSC_S_ERR		0x00000100
+#define BSC_S_RXF		0x00000080
+#define BSC_S_TXE		0x00000040
+#define BSC_S_RXD		0x00000020
+#define BSC_S_TXD		0x00000010
+#define BSC_S_RXR		0x00000008
+#define BSC_S_TXW		0x00000004
+#define BSC_S_DONE		0x00000002
+#define BSC_S_TA		0x00000001
+
+#define I2C_WAIT_LOOP_COUNT	200
+
+#define DRV_NAME		"bcm2708_i2c"
+
+static unsigned int baudrate;
+module_param(baudrate, uint, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
+MODULE_PARM_DESC(baudrate, "The I2C baudrate");
+
+static bool combined = false;
+module_param(combined, bool, 0644);
+MODULE_PARM_DESC(combined, "Use combined transactions");
+
+struct bcm2708_i2c {
+	struct i2c_adapter adapter;
+
+	spinlock_t lock;
+	void __iomem *base;
+	int irq;
+	struct clk *clk;
+	u32 cdiv;
+	u32 clk_tout;
+
+	struct completion done;
+
+	struct i2c_msg *msg;
+	int pos;
+	int nmsgs;
+	bool error;
+};
+
+static inline u32 bcm2708_rd(struct bcm2708_i2c *bi, unsigned reg)
+{
+	return readl(bi->base + reg);
+}
+
+static inline void bcm2708_wr(struct bcm2708_i2c *bi, unsigned reg, u32 val)
+{
+	writel(val, bi->base + reg);
+}
+
+static inline void bcm2708_bsc_reset(struct bcm2708_i2c *bi)
+{
+	bcm2708_wr(bi, BSC_C, 0);
+	bcm2708_wr(bi, BSC_S, BSC_S_CLKT | BSC_S_ERR | BSC_S_DONE);
+}
+
+static inline void bcm2708_bsc_fifo_drain(struct bcm2708_i2c *bi)
+{
+	while ((bi->pos < bi->msg->len) && (bcm2708_rd(bi, BSC_S) & BSC_S_RXD))
+		bi->msg->buf[bi->pos++] = bcm2708_rd(bi, BSC_FIFO);
+}
+
+static inline void bcm2708_bsc_fifo_fill(struct bcm2708_i2c *bi)
+{
+	while ((bi->pos < bi->msg->len) && (bcm2708_rd(bi, BSC_S) & BSC_S_TXD))
+		bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]);
+}
+
+static inline int bcm2708_bsc_setup(struct bcm2708_i2c *bi)
+{
+	u32 cdiv, s, clk_tout;
+	u32 c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_ST | BSC_C_CLEAR_1;
+	int wait_loops = I2C_WAIT_LOOP_COUNT;
+
+	/* Can't call clk_get_rate as it locks a mutex and here we are spinlocked.
+	 * Use the value that we cached in the probe.
+	 */
+	cdiv = bi->cdiv;
+	clk_tout = bi->clk_tout;
+
+	if (bi->msg->flags & I2C_M_RD)
+		c |= BSC_C_INTR | BSC_C_READ;
+	else
+		c |= BSC_C_INTT;
+
+	bcm2708_wr(bi, BSC_CLKT, clk_tout);
+	bcm2708_wr(bi, BSC_DIV, cdiv);
+	bcm2708_wr(bi, BSC_A, bi->msg->addr);
+	bcm2708_wr(bi, BSC_DLEN, bi->msg->len);
+	if (combined)
+	{
+		/* Do the next two messages meet combined transaction criteria?
+		   - Current message is a write, next message is a read
+		   - Both messages to same slave address
+		   - Write message can fit inside FIFO (16 bytes or less) */
+		if ( (bi->nmsgs > 1) &&
+			!(bi->msg[0].flags & I2C_M_RD) && (bi->msg[1].flags & I2C_M_RD) &&
+			 (bi->msg[0].addr == bi->msg[1].addr) && (bi->msg[0].len <= 16)) {
+
+			/* Clear FIFO */
+			bcm2708_wr(bi, BSC_C, BSC_C_CLEAR_1);
+
+			/* Fill FIFO with entire write message (16 byte FIFO) */
+			while (bi->pos < bi->msg->len) {
+				bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]);
+			}
+			/* Start write transfer (no interrupts, don't clear FIFO) */
+			bcm2708_wr(bi, BSC_C, BSC_C_I2CEN | BSC_C_ST);
+
+			/* poll for transfer start bit (should only take 1-20 polls) */
+			do {
+				s = bcm2708_rd(bi, BSC_S);
+			} while (!(s & (BSC_S_TA | BSC_S_ERR | BSC_S_CLKT | BSC_S_DONE)) && --wait_loops >= 0);
+
+			/* did we time out or some error occured? */
+			if (wait_loops < 0 || (s & (BSC_S_ERR | BSC_S_CLKT))) {
+				return -1;
+			}
+
+			/* Send next read message before the write transfer finishes. */
+			bi->nmsgs--;
+			bi->msg++;
+			bi->pos = 0;
+			bcm2708_wr(bi, BSC_DLEN, bi->msg->len);
+			c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_INTR | BSC_C_ST | BSC_C_READ;
+		}
+	}
+	bcm2708_wr(bi, BSC_C, c);
+
+	return 0;
+}
+
+static irqreturn_t bcm2708_i2c_interrupt(int irq, void *dev_id)
+{
+	struct bcm2708_i2c *bi = dev_id;
+	bool handled = true;
+	u32 s;
+	int ret;
+
+	spin_lock(&bi->lock);
+
+	/* we may see camera interrupts on the "other" I2C channel
+		   Just return if we've not sent anything */
+	if (!bi->nmsgs || !bi->msg) {
+		goto early_exit;
+	}
+
+	s = bcm2708_rd(bi, BSC_S);
+
+	if (s & (BSC_S_CLKT | BSC_S_ERR)) {
+		bcm2708_bsc_reset(bi);
+		bi->error = true;
+
+		bi->msg = 0; /* to inform the that all work is done */
+		bi->nmsgs = 0;
+		/* wake up our bh */
+		complete(&bi->done);
+	} else if (s & BSC_S_DONE) {
+		bi->nmsgs--;
+
+		if (bi->msg->flags & I2C_M_RD) {
+			bcm2708_bsc_fifo_drain(bi);
+		}
+
+		bcm2708_bsc_reset(bi);
+
+		if (bi->nmsgs) {
+			/* advance to next message */
+			bi->msg++;
+			bi->pos = 0;
+			ret = bcm2708_bsc_setup(bi);
+			if (ret < 0) {
+				bcm2708_bsc_reset(bi);
+				bi->error = true;
+				bi->msg = 0; /* to inform the that all work is done */
+				bi->nmsgs = 0;
+				/* wake up our bh */
+				complete(&bi->done);
+				goto early_exit;
+			}
+		} else {
+			bi->msg = 0; /* to inform the that all work is done */
+			bi->nmsgs = 0;
+			/* wake up our bh */
+			complete(&bi->done);
+		}
+	} else if (s & BSC_S_TXW) {
+		bcm2708_bsc_fifo_fill(bi);
+	} else if (s & BSC_S_RXR) {
+		bcm2708_bsc_fifo_drain(bi);
+	} else {
+		handled = false;
+	}
+
+early_exit:
+	spin_unlock(&bi->lock);
+
+	return handled ? IRQ_HANDLED : IRQ_NONE;
+}
+
+static int bcm2708_i2c_master_xfer(struct i2c_adapter *adap,
+	struct i2c_msg *msgs, int num)
+{
+	struct bcm2708_i2c *bi = adap->algo_data;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&bi->lock, flags);
+
+	reinit_completion(&bi->done);
+	bi->msg = msgs;
+	bi->pos = 0;
+	bi->nmsgs = num;
+	bi->error = false;
+
+	ret = bcm2708_bsc_setup(bi);
+
+	spin_unlock_irqrestore(&bi->lock, flags);
+
+	/* check the result of the setup */
+	if (ret < 0)
+	{
+		dev_err(&adap->dev, "transfer setup timed out\n");
+		goto error_timeout;
+	}
+
+	ret = wait_for_completion_timeout(&bi->done, adap->timeout);
+	if (ret == 0) {
+		dev_err(&adap->dev, "transfer timed out\n");
+		goto error_timeout;
+	}
+
+	ret = bi->error ? -EIO : num;
+	return ret;
+
+error_timeout:
+	spin_lock_irqsave(&bi->lock, flags);
+	bcm2708_bsc_reset(bi);
+	bi->msg = 0; /* to inform the interrupt handler that there's nothing else to be done */
+	bi->nmsgs = 0;
+	spin_unlock_irqrestore(&bi->lock, flags);
+	return -ETIMEDOUT;
+}
+
+static u32 bcm2708_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | /*I2C_FUNC_10BIT_ADDR |*/ I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm bcm2708_i2c_algorithm = {
+	.master_xfer = bcm2708_i2c_master_xfer,
+	.functionality = bcm2708_i2c_functionality,
+};
+
+static int bcm2708_i2c_probe(struct platform_device *pdev)
+{
+	struct resource *regs;
+	int irq, err = -ENOMEM;
+	struct clk *clk;
+	struct bcm2708_i2c *bi;
+	struct i2c_adapter *adap;
+	unsigned long bus_hz;
+	u32 cdiv, clk_tout;
+	u32 baud;
+
+	baud = CONFIG_I2C_BCM2708_BAUDRATE;
+
+	if (pdev->dev.of_node) {
+		u32 bus_clk_rate;
+		pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
+		if (pdev->id < 0) {
+			dev_err(&pdev->dev, "alias is missing\n");
+			return -EINVAL;
+		}
+		if (!of_property_read_u32(pdev->dev.of_node,
+					"clock-frequency", &bus_clk_rate))
+			baud = bus_clk_rate;
+		else
+			dev_warn(&pdev->dev,
+				"Could not read clock-frequency property\n");
+	}
+
+	if (baudrate)
+		baud = baudrate;
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!regs) {
+		dev_err(&pdev->dev, "could not get IO memory\n");
+		return -ENXIO;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "could not get IRQ\n");
+		return irq;
+	}
+
+	clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "could not find clk: %ld\n", PTR_ERR(clk));
+		return PTR_ERR(clk);
+	}
+
+	err = clk_prepare_enable(clk);
+	if (err) {
+		dev_err(&pdev->dev, "could not enable clk: %d\n", err);
+		goto out_clk_put;
+	}
+
+	bi = kzalloc(sizeof(*bi), GFP_KERNEL);
+	if (!bi)
+		goto out_clk_disable;
+
+	platform_set_drvdata(pdev, bi);
+
+	adap = &bi->adapter;
+	adap->class = I2C_CLASS_HWMON | I2C_CLASS_DDC;
+	adap->algo = &bcm2708_i2c_algorithm;
+	adap->algo_data = bi;
+	adap->dev.parent = &pdev->dev;
+	adap->nr = pdev->id;
+	strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));
+	adap->dev.of_node = pdev->dev.of_node;
+
+	switch (pdev->id) {
+	case 0:
+		adap->class = I2C_CLASS_HWMON;
+		break;
+	case 1:
+		adap->class = I2C_CLASS_DDC;
+		break;
+	case 2:
+		adap->class = I2C_CLASS_DDC;
+		break;
+	default:
+		dev_err(&pdev->dev, "can only bind to BSC 0, 1 or 2\n");
+		err = -ENXIO;
+		goto out_free_bi;
+	}
+
+	spin_lock_init(&bi->lock);
+	init_completion(&bi->done);
+
+	bi->base = ioremap(regs->start, resource_size(regs));
+	if (!bi->base) {
+		dev_err(&pdev->dev, "could not remap memory\n");
+		goto out_free_bi;
+	}
+
+	bi->irq = irq;
+	bi->clk = clk;
+
+	err = request_irq(irq, bcm2708_i2c_interrupt, IRQF_SHARED,
+			dev_name(&pdev->dev), bi);
+	if (err) {
+		dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
+		goto out_iounmap;
+	}
+
+	bcm2708_bsc_reset(bi);
+
+	err = i2c_add_numbered_adapter(adap);
+	if (err < 0) {
+		dev_err(&pdev->dev, "could not add I2C adapter: %d\n", err);
+		goto out_free_irq;
+	}
+
+	bus_hz = clk_get_rate(bi->clk);
+	cdiv = bus_hz / baud;
+	if (cdiv > 0xffff) {
+		cdiv = 0xffff;
+		baud = bus_hz / cdiv;
+	}
+
+	clk_tout = 35/1000*baud; //35ms timeout as per SMBus specs.
+	if (clk_tout > 0xffff)
+		clk_tout = 0xffff;
+	
+	bi->cdiv = cdiv;
+	bi->clk_tout = clk_tout;
+
+	dev_info(&pdev->dev, "BSC%d Controller at 0x%08lx (irq %d) (baudrate %d)\n",
+		pdev->id, (unsigned long)regs->start, irq, baud);
+
+	return 0;
+
+out_free_irq:
+	free_irq(bi->irq, bi);
+out_iounmap:
+	iounmap(bi->base);
+out_free_bi:
+	kfree(bi);
+out_clk_disable:
+	clk_disable_unprepare(clk);
+out_clk_put:
+	clk_put(clk);
+	return err;
+}
+
+static int bcm2708_i2c_remove(struct platform_device *pdev)
+{
+	struct bcm2708_i2c *bi = platform_get_drvdata(pdev);
+
+	platform_set_drvdata(pdev, NULL);
+
+	i2c_del_adapter(&bi->adapter);
+	free_irq(bi->irq, bi);
+	iounmap(bi->base);
+	clk_disable_unprepare(bi->clk);
+	clk_put(bi->clk);
+	kfree(bi);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2708_i2c_of_match[] = {
+        { .compatible = "brcm,bcm2708-i2c" },
+        {},
+};
+MODULE_DEVICE_TABLE(of, bcm2708_i2c_of_match);
+
+static struct platform_driver bcm2708_i2c_driver = {
+	.driver		= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+		.of_match_table = bcm2708_i2c_of_match,
+	},
+	.probe		= bcm2708_i2c_probe,
+	.remove		= bcm2708_i2c_remove,
+};
+
+// module_platform_driver(bcm2708_i2c_driver);
+
+
+static int __init bcm2708_i2c_init(void)
+{
+	return platform_driver_register(&bcm2708_i2c_driver);
+}
+
+static void __exit bcm2708_i2c_exit(void)
+{
+	platform_driver_unregister(&bcm2708_i2c_driver);
+}
+
+module_init(bcm2708_i2c_init);
+module_exit(bcm2708_i2c_exit);
+
+
+
+MODULE_DESCRIPTION("BSC controller driver for Broadcom BCM2708");
+MODULE_AUTHOR("Chris Boot <bootc@bootc.net>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);