[2/2] i2c: driver for the Conexant Digicolor I2C controller
diff mbox

Message ID a106023efa9fd648f46021cd063437df798528de.1424092804.git.baruch@tkos.co.il
State New, archived
Headers show

Commit Message

Baruch Siach Feb. 16, 2015, 1:20 p.m. UTC
This commit adds a driver for the I2C master controller on the CX92755 SoC. The
CX92755 is one SoC in the Conexant Digicolor series. This driver should support
other SoCs from that series.

Only 7bit slave addresses are currently supported.

Tested on the Equinox CX92755 EVK, using i2c-tools utilities to read and write
the on-chip (sic) audio codec.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
 drivers/i2c/busses/Kconfig         |   9 +
 drivers/i2c/busses/Makefile        |   1 +
 drivers/i2c/busses/i2c-digicolor.c | 384 +++++++++++++++++++++++++++++++++++++
 3 files changed, 394 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-digicolor.c

Comments

Wolfram Sang March 18, 2015, 9:07 p.m. UTC | #1
Hi,

On Mon, Feb 16, 2015 at 03:20:04PM +0200, Baruch Siach wrote:
> This commit adds a driver for the I2C master controller on the CX92755 SoC. The
> CX92755 is one SoC in the Conexant Digicolor series. This driver should support
> other SoCs from that series.
> 
> Only 7bit slave addresses are currently supported.
> 
> Tested on the Equinox CX92755 EVK, using i2c-tools utilities to read and write
> the on-chip (sic) audio codec.
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>

Looks mostly good.

> +static u32 dc_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}

You probably want to advertise I2C_FUNC_NOSTART here, too?

And if you could rebase to something after 4.0-rc1, that would be much
appreciated.

Thanks,

   Wolfram
Baruch Siach March 19, 2015, 9:30 a.m. UTC | #2
Hi Wolfram,

On Wed, Mar 18, 2015 at 10:07:30PM +0100, Wolfram Sang wrote:
> On Mon, Feb 16, 2015 at 03:20:04PM +0200, Baruch Siach wrote:
> > This commit adds a driver for the I2C master controller on the CX92755 SoC. The
> > CX92755 is one SoC in the Conexant Digicolor series. This driver should support
> > other SoCs from that series.
> > 
> > Only 7bit slave addresses are currently supported.
> > 
> > Tested on the Equinox CX92755 EVK, using i2c-tools utilities to read and write
> > the on-chip (sic) audio codec.
> > 
> > Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> 
> Looks mostly good.
> 
> > +static u32 dc_i2c_func(struct i2c_adapter *adap)
> > +{
> > +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> > +}
> 
> You probably want to advertise I2C_FUNC_NOSTART here, too?

OK.

> And if you could rebase to something after 4.0-rc1, that would be much
> appreciated.

Did that some time ago along with the rest of my queue for that platform. Just 
waited for some review before reposting.

Thanks for reviewing,
baruch

Patch
diff mbox

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 31e8308ba899..08cf8acf87aa 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -465,6 +465,15 @@  config I2C_DESIGNWARE_PCI
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-designware-pci.
 
+config I2C_DIGICOLOR
+	tristate "Conexang Digicolor I2C driver"
+	depends on ARCH_DIGICOLOR
+	help
+	  Support for Conexant Digicolor SoCs (CX92755) I2C controller driver.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-digicolor.
+
 config I2C_EFM32
 	tristate "EFM32 I2C controller"
 	depends on ARCH_EFM32 || COMPILE_TEST
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 56388f658d2f..1b1830d50651 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -43,6 +43,7 @@  obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM)	+= i2c-designware-platform.o
 i2c-designware-platform-objs := i2c-designware-platdrv.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+= i2c-designware-pci.o
 i2c-designware-pci-objs := i2c-designware-pcidrv.o
+obj-$(CONFIG_I2C_DIGICOLOR)	+= i2c-digicolor.o
 obj-$(CONFIG_I2C_EFM32)		+= i2c-efm32.o
 obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
 obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
diff --git a/drivers/i2c/busses/i2c-digicolor.c b/drivers/i2c/busses/i2c-digicolor.c
new file mode 100644
index 000000000000..0ec0eafb8fb6
--- /dev/null
+++ b/drivers/i2c/busses/i2c-digicolor.c
@@ -0,0 +1,384 @@ 
+/*
+ * I2C bus driver for Conexant Digicolor SoCs
+ *
+ * Author: Baruch Siach <baruch@tkos.co.il>
+ *
+ * Copyright (C) 2015 Paradox Innovation Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define DEFAULT_FREQ		100000
+#define TIMEOUT_MS		100
+
+#define II_CONTROL		0x0
+#define II_CONTROL_LOCAL_RESET	BIT(0)
+
+#define II_CLOCKTIME		0x1
+
+#define II_COMMAND		0x2
+#define II_CMD_START		1
+#define II_CMD_RESTART		2
+#define II_CMD_SEND_ACK		3
+#define II_CMD_GET_ACK		6
+#define II_CMD_GET_NOACK	7
+#define II_CMD_STOP		10
+#define II_COMMAND_GO		BIT(7)
+#define II_COMMAND_COMPLETION_STATUS(r)	(((r) >> 5) & 3)
+#define II_CMD_STATUS_NORMAL	0
+#define II_CMD_STATUS_ACK_GOOD	1
+#define II_CMD_STATUS_ACK_BAD	2
+#define II_CMD_STATUS_ABORT	3
+
+#define II_DATA			0x3
+#define II_INTFLAG_CLEAR	0x8
+#define II_INTENABLE		0xa
+
+struct dc_i2c {
+	struct i2c_adapter	adap;
+	struct device		*dev;
+	void __iomem		*regs;
+	struct clk		*clk;
+	unsigned int		frequency;
+
+	struct i2c_msg		*msg;
+	unsigned int		msgbuf_ptr;
+	int			last;
+	spinlock_t		lock;
+	struct completion	done;
+	int			state;
+	int			error;
+};
+
+enum {
+        STATE_IDLE,
+        STATE_START,
+        STATE_ADDR,
+        STATE_WRITE,
+        STATE_READ,
+        STATE_STOP,
+};
+
+static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
+{
+	writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
+}
+
+static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
+{
+	u8 addr = (msg->addr & 0x7f) << 1;
+
+	if (msg->flags & I2C_M_RD)
+		addr |= 1;
+
+	return addr;
+}
+
+static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
+{
+	writeb_relaxed(data, i2c->regs + II_DATA);
+}
+
+static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
+{
+	dc_i2c_data(i2c, byte);
+	dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
+}
+
+static void dc_i2c_write_buf(struct dc_i2c *i2c)
+{
+	dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
+}
+
+static void dc_i2c_next_read(struct dc_i2c *i2c)
+{
+	bool last = (i2c->msgbuf_ptr+1 == i2c->msg->len);
+	dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
+}
+
+static void dc_i2c_stop(struct dc_i2c *i2c)
+{
+	i2c->state = STATE_STOP;
+	if (i2c->last)
+		dc_i2c_cmd(i2c, II_CMD_STOP);
+	else
+		complete(&i2c->done);
+}
+
+static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
+{
+	return readb_relaxed(i2c->regs + II_DATA);
+}
+
+static void dc_i2c_read_buf(struct dc_i2c *i2c)
+{
+	i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
+	dc_i2c_next_read(i2c);
+}
+
+static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
+{
+	if (enable)
+		writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
+	writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
+}
+
+static int dc_i2c_cmd_status(struct dc_i2c *i2c)
+{
+	u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);
+
+	return II_COMMAND_COMPLETION_STATUS(cmd);
+}
+
+static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
+{
+	struct i2c_msg *msg = i2c->msg;
+
+	if (!(msg->flags & I2C_M_NOSTART)) {
+		i2c->state = STATE_START;
+		dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
+	} else if (msg->flags & I2C_M_RD) {
+		i2c->state = STATE_READ;
+		dc_i2c_next_read(i2c);
+	} else {
+		i2c->state = STATE_WRITE;
+		dc_i2c_write_buf(i2c);
+	}
+}
+
+static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
+{
+	struct dc_i2c *i2c = dev_id;
+	int cmd_status = dc_i2c_cmd_status(i2c);
+	unsigned long flags;
+	u8 addr_cmd;
+
+	writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
+
+	spin_lock_irqsave(&i2c->lock, flags);
+
+	if (cmd_status == II_CMD_STATUS_ACK_BAD
+	    || cmd_status == II_CMD_STATUS_ABORT) {
+		i2c->error = -EIO;
+		complete(&i2c->done);
+		goto out;
+	}
+
+	switch (i2c->state) {
+	case STATE_START:
+		addr_cmd = dc_i2c_addr_cmd(i2c->msg);
+		dc_i2c_write_byte(i2c, addr_cmd);
+		i2c->state = STATE_ADDR;
+		break;
+	case STATE_ADDR:
+		if (i2c->msg->flags & I2C_M_RD) {
+			dc_i2c_next_read(i2c);
+			i2c->state = STATE_READ;
+			break;
+		}
+		i2c->state = STATE_WRITE;
+		/* fall through */
+	case STATE_WRITE:
+		if (i2c->msgbuf_ptr < i2c->msg->len)
+			dc_i2c_write_buf(i2c);
+		else
+			dc_i2c_stop(i2c);
+		break;
+	case STATE_READ:
+		if (i2c->msgbuf_ptr < i2c->msg->len)
+			dc_i2c_read_buf(i2c);
+		else
+			dc_i2c_stop(i2c);
+		break;
+	case STATE_STOP:
+		i2c->state = STATE_IDLE;
+		complete(&i2c->done);
+		break;
+	}
+
+out:
+	spin_unlock_irqrestore(&i2c->lock, flags);
+	return IRQ_HANDLED;
+}
+
+static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
+			   int last)
+{
+	unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS);
+	unsigned long flags;
+
+	spin_lock_irqsave(&i2c->lock, flags);
+	i2c->msg = msg;
+	i2c->msgbuf_ptr = 0;
+	i2c->last = last;
+	i2c->error = 0;
+
+	reinit_completion(&i2c->done);
+	dc_i2c_set_irq(i2c, 1);
+	dc_i2c_start_msg(i2c, first);
+	spin_unlock_irqrestore(&i2c->lock, flags);
+
+	timeout = wait_for_completion_timeout(&i2c->done, timeout);
+	dc_i2c_set_irq(i2c, 0);
+	if (timeout == 0) {
+		i2c->state = STATE_IDLE;
+		return -ETIMEDOUT;
+	}
+
+	if (i2c->error)
+		return i2c->error;
+
+	return 0;
+}
+
+static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct dc_i2c *i2c = adap->algo_data;
+	int i, ret;
+
+	for (i = 0; i < num; i++) {
+		ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static int dc_i2c_init_hw(struct dc_i2c *i2c)
+{
+	unsigned long clk_rate = clk_get_rate(i2c->clk);
+	unsigned int clocktime;
+
+	writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
+	udelay(100);
+	writeb_relaxed(0, i2c->regs + II_CONTROL);
+	udelay(100);
+
+	clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
+	if (clocktime < 1 || clocktime > 0xff) {
+		dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
+			i2c->frequency);
+		return -EINVAL;
+	}
+	writeb_relaxed(clocktime-1, i2c->regs + II_CLOCKTIME);
+
+	return 0;
+}
+
+static u32 dc_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm dc_i2c_algorithm = {
+	.master_xfer	= dc_i2c_xfer,
+	.functionality	= dc_i2c_func,
+};
+
+static int dc_i2c_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct dc_i2c *i2c;
+	struct resource *r;
+	int ret = 0, irq;
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+				 &i2c->frequency))
+		i2c->frequency = DEFAULT_FREQ;
+
+	i2c->dev = &pdev->dev;
+	platform_set_drvdata(pdev, i2c);
+
+	spin_lock_init(&i2c->lock);
+	init_completion(&i2c->done);
+
+	i2c->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(i2c->clk))
+		return PTR_ERR(i2c->clk);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	i2c->regs = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(i2c->regs))
+		return PTR_ERR(i2c->regs);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
+			       dev_name(&pdev->dev), i2c);
+	if (ret < 0)
+		return ret;
+
+	strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
+		sizeof(i2c->adap.name));
+	i2c->adap.owner = THIS_MODULE;
+	i2c->adap.algo = &dc_i2c_algorithm;
+	i2c->adap.dev.parent = &pdev->dev;
+	i2c->adap.dev.of_node = np;
+	i2c->adap.algo_data = i2c;
+
+	ret = dc_i2c_init_hw(i2c);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(i2c->clk);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret < 0) {
+		clk_unprepare(i2c->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dc_i2c_remove(struct platform_device *pdev)
+{
+	struct dc_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	clk_disable_unprepare(i2c->clk);
+
+	return 0;
+}
+
+static const struct of_device_id dc_i2c_match[] = {
+	{ .compatible = "cnxt,cx92755-i2c" },
+	{ },
+};
+
+static struct platform_driver dc_i2c_driver = {
+	.probe   = dc_i2c_probe,
+	.remove  = dc_i2c_remove,
+	.driver  = {
+		.name  = "digicolor-i2c",
+		.of_match_table = dc_i2c_match,
+	},
+};
+module_platform_driver(dc_i2c_driver);
+
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("Conexant Digicolor I2C master driver");
+MODULE_LICENSE("GPL v2");