Re: [PATCH 1/2] I2C: EMMA Mobile I2C master driver

[Simon Horman <horms@verge.net.au>]

On Tue, Sep 03, 2013 at 05:49:29PM +0100, Ian Molton wrote:
> Add a driver for the EMMA mobile I2C block.
> 
> The driver supports low and high-speed interrupt driven PIO transfers.
> 
> Signed-off-by: Ian Molton <ian.molton@codethink.co.uk>

Magnus, could you find some time to review this?

> ---
>  drivers/i2c/busses/Kconfig  |   10 +
>  drivers/i2c/busses/Makefile |    1 +
>  drivers/i2c/busses/i2c-em.c |  501 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 512 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-em.c
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index dc6dea6..d66d4b4 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -777,6 +777,16 @@ config I2C_RCAR
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called i2c-rcar.
>  
> +config I2C_EM
> +	tristate "EMMA Mobile series I2C adapter"
> +	depends on I2C && HAVE_CLK
> +	help
> +	  If you say yes to this option, support will be included for the
> +	  I2C interface on the Renesas Electronics EM/EV family of processors.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called i2c-em
> +
>  comment "External I2C/SMBus adapter drivers"
>  
>  config I2C_DIOLAN_U2C
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index d00997f..d330706 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -42,6 +42,7 @@ 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_EG20T)		+= i2c-eg20t.o
> +obj-$(CONFIG_I2C_EM)            += i2c-em.o
>  obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
>  obj-$(CONFIG_I2C_HIGHLANDER)	+= i2c-highlander.o
>  obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
> diff --git a/drivers/i2c/busses/i2c-em.c b/drivers/i2c/busses/i2c-em.c
> new file mode 100644
> index 0000000..d7e91b4
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-em.c
> @@ -0,0 +1,501 @@
> +/*
> + * Copyright 2013 Codethink Ltd.
> + * Parts Copyright 2010 Renesas Electronics Corporation
> + *
> + * 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.
> + *
> + * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/delay.h>
> +#include <linux/of_i2c.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/sched.h>
> +
> +#include <linux/interrupt.h>
> +#include <linux/device.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +
> +/* I2C Registers */
> +#define I2C_OFS_IICACT0		0x00	/* start */
> +#define I2C_OFS_IIC0		0x04	/* shift */
> +#define I2C_OFS_IICC0		0x08	/* control */
> +#define I2C_OFS_SVA0		0x0c	/* slave address */
> +#define I2C_OFS_IICCL0		0x10	/* clock select */
> +#define I2C_OFS_IICX0		0x14	/* extention */
> +#define I2C_OFS_IICS0		0x18	/* status */
> +#define I2C_OFS_IICSE0		0x1c	/* status For emulation */
> +#define I2C_OFS_IICF0		0x20	/* IIC flag */
> +
> +/* I2C IICACT0 Masks */
> +#define I2C_BIT_IICE0		0x0001
> +
> +/* I2C IICC0 Masks */
> +#define I2C_BIT_LREL0		0x0040
> +#define I2C_BIT_WREL0		0x0020
> +#define I2C_BIT_SPIE0		0x0010
> +#define I2C_BIT_WTIM0		0x0008
> +#define I2C_BIT_ACKE0		0x0004
> +#define I2C_BIT_STT0		0x0002
> +#define I2C_BIT_SPT0		0x0001
> +
> +/* I2C IICCL0 Masks */
> +#define I2C_BIT_SMC0		0x0008
> +#define I2C_BIT_DFC0		0x0004
> +
> +/* I2C IICSE0 Masks */
> +#define I2C_BIT_MSTS0		0x0080
> +#define I2C_BIT_ALD0		0x0040
> +#define I2C_BIT_EXC0		0x0020
> +#define I2C_BIT_COI0		0x0010
> +#define I2C_BIT_TRC0		0x0008
> +#define I2C_BIT_ACKD0		0x0004
> +#define I2C_BIT_STD0		0x0002
> +#define I2C_BIT_SPD0		0x0001
> +
> +/* I2C IICF0 Masks */
> +#define I2C_BIT_STCF		0x0080
> +#define I2C_BIT_IICBSY		0x0040
> +#define I2C_BIT_STCEN		0x0002
> +#define I2C_BIT_IICRSV		0x0001
> +
> +static int em_i2c_xfer(struct i2c_adapter *, struct i2c_msg[], int);
> +
> +struct em_i2c_device {
> +	struct i2c_adapter	adap;
> +	wait_queue_head_t	i2c_wait;
> +	void __iomem		*membase;
> +	struct clk              *clk;
> +	struct clk              *sclk;
> +	int			irq;
> +	int			flags;
> +	int			pending;
> +	spinlock_t              irq_lock;
> +};
> +
> +#define to_em_i2c(adap) (struct em_i2c_device *)i2c_get_adapdata(adap)
> +
> +static u32 em_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static struct i2c_algorithm em_i2c_algo = {
> +	.master_xfer = em_i2c_xfer,
> +	.smbus_xfer = NULL,
> +	.functionality = em_i2c_func,
> +};
> +
> +static void em_i2c_enable_clock(struct em_i2c_device *i2c_dev)
> +{
> +	clk_enable(i2c_dev->clk);
> +	clk_enable(i2c_dev->sclk);
> +}
> +
> +static void em_i2c_disable_clock(struct em_i2c_device *i2c_dev)
> +{
> +	clk_disable(i2c_dev->sclk);
> +	clk_disable(i2c_dev->clk);
> +}
> +
> +static int em_i2c_wait_for_event(struct em_i2c_device *i2c_dev, u16 *status)
> +{
> +	int interrupted;
> +
> +	do {
> +		interrupted = wait_event_interruptible_timeout(
> +				i2c_dev->i2c_wait, i2c_dev->pending,
> +				i2c_dev->adap.timeout);
> +
> +		if (i2c_dev->pending) {
> +			spin_lock_irq(&i2c_dev->irq_lock);
> +			i2c_dev->pending = 0;
> +			spin_unlock_irq(&i2c_dev->irq_lock);
> +			*status = readl(i2c_dev->membase + I2C_OFS_IICSE0);
> +			return 0;
> +		}
> +
> +	} while (interrupted);
> +
> +	*status = 0;
> +
> +	return -ETIMEDOUT;
> +}
> +
> +static int em_i2c_stop(struct em_i2c_device *i2c_dev)
> +{
> +	u16 status;
> +
> +	/* Send Stop condition */
> +	writel((readl(i2c_dev->membase + I2C_OFS_IICC0) | I2C_BIT_SPT0 |
> +		I2C_BIT_SPIE0), i2c_dev->membase + I2C_OFS_IICC0);
> +
> +	/* Wait for stop condition */
> +	em_i2c_wait_for_event(i2c_dev, &status);
> +	/* FIXME - check status? */
> +
> +	if ((readl(i2c_dev->membase + I2C_OFS_IICSE0) & I2C_BIT_SPD0) != 0)
> +		return 0;
> +
> +	return -EBUSY;
> +}
> +
> +static int em_i2c_start(struct em_i2c_device *i2c_dev)
> +{
> +	/* Send start condition */
> +	writel((readl(i2c_dev->membase + I2C_OFS_IICC0)) | I2C_BIT_ACKE0 |
> +		I2C_BIT_WTIM0, i2c_dev->membase + I2C_OFS_IICC0);
> +
> +	writel((readl(i2c_dev->membase + I2C_OFS_IICC0) | I2C_BIT_STT0),
> +		i2c_dev->membase + I2C_OFS_IICC0);
> +
> +	return -EBUSY;
> +}
> +
> +static void em_i2c_reset(struct i2c_adapter *adap)
> +{
> +	struct em_i2c_device *i2c_dev = to_em_i2c(adap);
> +	int retr;
> +
> +	/* If I2C active */
> +	if (readl(i2c_dev->membase + I2C_OFS_IICACT0) & I2C_BIT_IICE0) {
> +
> +		/* Disable I2C operation */
> +		writel(0, i2c_dev->membase + I2C_OFS_IICACT0);
> +
> +		retr = 1000;
> +		while (readl(i2c_dev->membase + I2C_OFS_IICACT0) == 1 && retr)
> +			retr--;
> +		WARN_ON(retr == 0);
> +	}
> +
> +	/* Transfer mode set */
> +	writel(i2c_dev->flags, i2c_dev->membase + I2C_OFS_IICCL0);
> +
> +	/* Can Issue start without detecting a stop, Reservation disabled. */
> +	writel(I2C_BIT_STCEN | I2C_BIT_IICRSV,
> +		i2c_dev->membase + I2C_OFS_IICF0);
> +
> +	/* I2C enable, 9 bit interrupt mode */
> +	writel(I2C_BIT_WTIM0, i2c_dev->membase + I2C_OFS_IICC0);
> +
> +	/* Enable I2C operation */
> +	writel(I2C_BIT_IICE0, i2c_dev->membase + I2C_OFS_IICACT0);
> +
> +	retr = 1000;
> +	while (readl(i2c_dev->membase + I2C_OFS_IICACT0) == 0 && retr)
> +		retr--;
> +	WARN_ON(retr == 0);
> +}
> +
> +static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
> +				int stop)
> +{
> +	struct em_i2c_device *i2c_dev = to_em_i2c(adap);
> +	int count = 0;
> +	u16 status;
> +
> +	/* Start transfer */
> +	em_i2c_start(i2c_dev);
> +
> +	/* Send slave address and R/W type */
> +	writel((msg->addr << 1) | ((msg->flags & I2C_M_RD) ? 1 : 0),
> +		i2c_dev->membase + I2C_OFS_IIC0);
> +
> +	/* Wait for transaction */
> +	if (em_i2c_wait_for_event(i2c_dev, &status))
> +		goto out_reset;
> +
> +	/* Arbitration, Extension mode or Slave mode are all errors */
> +	if (status & (I2C_BIT_EXC0 | I2C_BIT_COI0 | I2C_BIT_ALD0)
> +			|| !(status & I2C_BIT_MSTS0))
> +		goto out_reset;
> +
> +	/* Extra setup for read transactions */
> +	if (!(status & I2C_BIT_TRC0)) {
> +
> +		/* msg->flags is Write type */
> +		if (!(msg->flags & I2C_M_RD))
> +			goto out_reset;
> +
> +		/* Recieved No ACK (result of setting slave address and R/W) */
> +		if (!(status & I2C_BIT_ACKD0)) {
> +			em_i2c_stop(i2c_dev);
> +			goto out;
> +		}
> +
> +		/* 8 bit interrupt mode */
> +		writel((readl(i2c_dev->membase + I2C_OFS_IICC0)
> +				& ~I2C_BIT_WTIM0) | I2C_BIT_ACKE0,
> +				i2c_dev->membase + I2C_OFS_IICC0);
> +		writel((readl(i2c_dev->membase + I2C_OFS_IICC0)
> +				& ~I2C_BIT_WTIM0) | I2C_BIT_WREL0,
> +				i2c_dev->membase + I2C_OFS_IICC0);
> +
> +		/* Wait for transaction */
> +		if (em_i2c_wait_for_event(i2c_dev, &status))
> +			goto out_reset;
> +	}
> +
> +	/* Send / receive data */
> +	do {
> +		/* Arbitration, Extension mode or Slave mode are errors*/
> +		if (status & (I2C_BIT_EXC0 | I2C_BIT_COI0 | I2C_BIT_ALD0)
> +				|| !(status & I2C_BIT_MSTS0))
> +			goto out_reset;
> +
> +		if (!(status & I2C_BIT_TRC0)) { /* Read transaction */
> +
> +			/* msg->flags is Write type */
> +			if (!(msg->flags & I2C_M_RD))
> +				goto out_reset;
> +
> +			if (count == msg->len)
> +				break;
> +
> +			msg->buf[count++] =
> +				readl(i2c_dev->membase + I2C_OFS_IIC0);
> +
> +
> +			writel((readl(i2c_dev->membase + I2C_OFS_IICC0)
> +				| I2C_BIT_WREL0),
> +				i2c_dev->membase + I2C_OFS_IICC0);
> +
> +		} else { /* Write transaction */
> +
> +			/* msg->flags is Read type */
> +			if ((msg->flags & I2C_M_RD))
> +				goto out_reset;
> +
> +			/* Recieved No ACK */
> +			if (!(status & I2C_BIT_ACKD0)) {
> +				em_i2c_stop(i2c_dev);
> +				goto out;
> +			}
> +
> +			if (count == msg->len)
> +				break;
> +
> +			/* Write data */
> +			writel(msg->buf[count++], i2c_dev->membase
> +				+ I2C_OFS_IIC0);
> +		}
> +
> +		/* Wait for R/W transaction */
> +		if (em_i2c_wait_for_event(i2c_dev, &status))
> +			goto out_reset;
> +
> +	} while (1);
> +
> +	if (stop)
> +		em_i2c_stop(i2c_dev);
> +
> +	return count;
> +
> +out_reset:
> +	em_i2c_reset(adap);
> +out:
> +	return -EREMOTEIO;
> +}
> +
> +static int em_i2c_wait_free(struct i2c_adapter *adap)
> +{
> +	struct em_i2c_device *i2c_dev = to_em_i2c(adap);
> +	int timeout = adap->timeout;
> +	int status;
> +
> +	/* wait until I2C bus free */
> +	while ((readl(i2c_dev->membase + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
> +			&& timeout--) {
> +		schedule_timeout_uninterruptible(1);
> +	}
> +
> +	status = (timeout <= 0);
> +
> +	if (status)
> +		dev_info(&adap->dev, "I2C bus is busy\n");
> +
> +	return status;
> +}
> +
> +static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> +	int num)
> +{
> +	struct em_i2c_device *i2c_dev = to_em_i2c(adap);
> +	int ret = 0;
> +	int i;
> +
> +	em_i2c_enable_clock(i2c_dev);
> +	em_i2c_reset(adap);
> +
> +	/* Attempt to gain control of the adapter */
> +	i = 0;
> +	while (em_i2c_wait_free(adap)) {
> +		switch (i) {
> +		case 0:
> +			if (!(readl(i2c_dev->membase + I2C_OFS_IICSE0)
> +					& I2C_BIT_MSTS0)) {
> +				/* Slave mode -> Error */
> +				ret = -EBUSY;
> +				goto out;
> +			}
> +
> +			em_i2c_stop(i2c_dev);
> +			break;
> +		case 1:
> +			em_i2c_reset(adap);
> +			break;
> +		case 2:
> +			ret = -EREMOTEIO;
> +			goto out;
> +		}
> +		i++;
> +	}
> +
> +	/* Send messages */
> +	for (i = 0; i < num; i++) {
> +		ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
> +		if (ret < 0)
> +			goto out;
> +	}
> +
> +	/* I2C transfer completed */
> +	ret = i;
> +
> +out:
> +	em_i2c_disable_clock(i2c_dev);
> +
> +	return ret;
> +}
> +
> +static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id)
> +{
> +	struct em_i2c_device *i2c_dev = dev_id;
> +
> +	i2c_dev->pending = 1;
> +
> +	wake_up_interruptible(&i2c_dev->i2c_wait);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int em_i2c_probe(struct platform_device *pdev)
> +{
> +	struct em_i2c_device *i2c_dev;
> +	struct resource *r;
> +	int ret;
> +
> +	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(struct em_i2c_device),
> +				GFP_KERNEL);
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	i2c_dev->membase = devm_ioremap_resource(&pdev->dev, r);
> +	if (IS_ERR(i2c_dev->membase))
> +		return PTR_ERR(i2c_dev->membase);
> +
> +	strlcpy(i2c_dev->adap.name, "em_i2c", sizeof(i2c_dev->adap.name));
> +
> +	i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (!IS_ERR(i2c_dev->clk))
> +		clk_prepare(i2c_dev->clk);
> +
> +	i2c_dev->sclk = devm_clk_get(&pdev->dev, "sclk");
> +	if (!IS_ERR(i2c_dev->sclk))
> +		clk_prepare(i2c_dev->sclk);
> +
> +	i2c_dev->irq = platform_get_irq(pdev, 0);
> +	i2c_dev->adap.timeout = msecs_to_jiffies(100);
> +	i2c_dev->adap.dev.parent = &pdev->dev;
> +	i2c_dev->adap.algo = &em_i2c_algo;
> +	i2c_dev->adap.owner = THIS_MODULE;
> +	i2c_dev->adap.nr = pdev->id;
> +	i2c_dev->adap.dev.of_node = pdev->dev.of_node;
> +
> +	init_waitqueue_head(&i2c_dev->i2c_wait);
> +
> +	spin_lock_init(&i2c_dev->irq_lock);
> +
> +	i2c_dev->flags = I2C_BIT_DFC0;
> +
> +	if (of_find_property(pdev->dev.of_node, "high-speed", NULL))
> +		i2c_dev->flags |= I2C_BIT_SMC0;
> +
> +	platform_set_drvdata(pdev, i2c_dev);
> +	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
> +
> +	em_i2c_enable_clock(i2c_dev);
> +	em_i2c_reset(&i2c_dev->adap);
> +	em_i2c_disable_clock(i2c_dev);
> +
> +	ret = devm_request_irq(&pdev->dev, i2c_dev->irq, em_i2c_irq_handler, 0,
> +				"em_i2c", i2c_dev);
> +
> +	if (ret)
> +		goto exit_clk;
> +
> +	ret = i2c_add_numbered_adapter(&i2c_dev->adap);
> +
> +	if (ret != 0)
> +		goto exit_clk;
> +
> +	of_i2c_register_devices(&i2c_dev->adap);
> +
> +	dev_info(&pdev->dev, "Added i2c controller %d irq %d @ 0x%p\n",
> +		i2c_dev->adap.nr, i2c_dev->irq, i2c_dev->membase);
> +
> +	return 0;
> +
> +exit_clk:
> +	clk_disable(i2c_dev->clk);
> +	clk_unprepare(i2c_dev->clk);
> +	return ret;
> +}
> +
> +static int em_i2c_remove(struct platform_device *dev)
> +{
> +	struct em_i2c_device *i2c_dev = platform_get_drvdata(dev);
> +
> +	i2c_del_adapter(&i2c_dev->adap);
> +
> +	clk_disable(i2c_dev->clk);
> +	clk_unprepare(i2c_dev->clk);
> +
> +	return 0;
> +}
> +
> +static struct of_device_id em_i2c_ids[] = {
> +	{ .compatible = "renesas,em-i2c", },
> +	{ }
> +};
> +
> +static struct platform_driver em_i2c_driver = {
> +	.probe = em_i2c_probe,
> +	.remove = em_i2c_remove,
> +	.driver = {
> +		.name = "em-i2c",
> +		.owner = THIS_MODULE,
> +		.of_match_table = em_i2c_ids,
> +	}
> +};
> +
> +module_platform_driver(em_i2c_driver);
> +MODULE_DEVICE_TABLE(of, em_i2c_ids);
> +
> +MODULE_LICENSE("GPLv2");
> +MODULE_DESCRIPTION("EMEV2 I2C bus driver");
> +MODULE_AUTHOR("Ian Molton");
> +
> -- 
> 1.7.10.4
> 
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