Subject: [PATCH 1/2] NUC900: Add i2c0 driver support for NUC900

From: [email-masked] (Ben Dooks)
Date: Sun, 20 Jun 2010 23:38:17 +0100

On Mon, Jun 14, 2010 at 01:24:12AM +0800, Wan ZongShun wrote:
> This patch is to add i2c0 driver support for NUC900.
> 
> Signed-off-by: Wan ZongShun <[email-masked]>
> 
> ---
>  arch/arm/mach-w90x900/include/mach/i2c.h |   11 +
>  drivers/i2c/busses/Kconfig               |    7 +
>  drivers/i2c/busses/Makefile              |    1 +
>  drivers/i2c/busses/i2c-nuc900.c          |  699 ++++++++++++++++++++++++++++++
>  4 files changed, 718 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arm/mach-w90x900/include/mach/i2c.h
>  create mode 100644 drivers/i2c/busses/i2c-nuc900.c
> 
> diff --git a/arch/arm/mach-w90x900/include/mach/i2c.h b/arch/arm/mach-w90x900/include/mach/i2c.h
> new file mode 100644
> index 0000000..292f3f9
> --- /dev/null
> +++ b/arch/arm/mach-w90x900/include/mach/i2c.h
> @@ -0,0 +1,11 @@
> +#ifndef __ASM_ARCH_NUC900_I2C_H
> +#define __ASM_ARCH_NUC900_I2C_H
> +
> +struct nuc900_platform_i2c {
> +	int		bus_num;
> +	unsigned long   bus_freq;
> +	void	(*get_clock)(unsigned int *cpuclk_khz,
> +			unsigned int *ahbclk_khz, unsigned int *apbclk_khz);
> +};
> +
> +#endif /* __ASM_ARCH_NUC900_I2C_H */
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index bceafbf..ee284d2 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -448,6 +448,13 @@ config I2C_NOMADIK
>  	  If you say yes to this option, support will be included for the
>  	  I2C interface from ST-Ericsson's Nomadik and Ux500 architectures.
> 
> +config I2C_NUC900
> +	tristate "NUC900 I2C Driver"
> +	depends on ARCH_W90X900
> +	help
> +	  Say Y here to include support for I2C controller in the
> +	  Winbond/Nuvoton NUC900 based System-on-Chip devices.
> +
>  config I2C_OCORES
>  	tristate "OpenCores I2C Controller"
>  	depends on EXPERIMENTAL
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 936880b..c3ef492 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -43,6 +43,7 @@ obj-$(CONFIG_I2C_IXP2000)	+= i2c-ixp2000.o
>  obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
>  obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
>  obj-$(CONFIG_I2C_NOMADIK)	+= i2c-nomadik.o
> +obj-$(CONFIG_I2C_NUC900)	+= i2c-nuc900.o
>  obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o
>  obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o
>  obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o
> diff --git a/drivers/i2c/busses/i2c-nuc900.c b/drivers/i2c/busses/i2c-nuc900.c
> new file mode 100644
> index 0000000..c8e043a
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-nuc900.c
> @@ -0,0 +1,699 @@
> +/*
> + * linux/drivers/i2c/busses/i2c-nuc900.c
> + *
> + * Copyright (c) 2010 Nuvoton technology corporation.
> + *
> + * This driver based on S3C2410 I2C Controller of Ben Dooks <[email-masked]>.
> + * Written by Wan ZongShun <[email-masked]>
> + *
> + * 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;version 2 of the License.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +#include <linux/i2c.h>
> +#include <linux/i2c-id.h>
> +#include <linux/init.h>
> +#include <linux/time.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/clk.h>
> +#include <linux/cpufreq.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +
> +#include <mach/mfp.h>
> +#include <mach/i2c.h>
> +
> +#define CSR		0x00
> +#define DIVIDER		0x04
> +#define CMDR		0x08
> +#define SWR		0x0C
> +#define RXR		0x10
> +#define TXR		0x14
> +
> +#define IRQEN		0x003
> +#define I2CBUSY		0x400
> +#define I2CSTART	0x018
> +
> +#define I2C_CMD_START	0x10
> +#define I2C_CMD_STOP	0x08
> +#define I2C_CMD_READ	0x04
> +#define I2C_CMD_WRITE	0x02
> +#define I2C_CMD_NACK	0x01
> +
> +#define IRQFLAG		0x004
> +#define ARBIT_LOST	0x200
> +#define SLAVE_ACK	0x800
> +
> +/* i2c controller state */
> +
> +enum nuc900_i2c_state {
> +	STATE_IDLE,
> +	STATE_START,
> +	STATE_READ,
> +	STATE_WRITE,
> +	STATE_STOP
> +};
> +
> +struct nuc900_i2c {
> +	spinlock_t		lock;
> +	wait_queue_head_t	wait;
> +
> +	struct i2c_msg		*msg;
> +	unsigned int		msg_num;
> +	unsigned int		msg_idx;
> +	unsigned int		msg_ptr;
> +	unsigned int		irq;
> +
> +	enum nuc900_i2c_state	state;
> +
> +	void __iomem		*regs;
> +	struct clk		*clk;
> +	struct device		*dev;
> +	struct resource		*ioarea;
> +	struct i2c_adapter	adap;
> +};

would be nice to document these.

> +/* nuc900_i2c_master_complete
> + *
> + * complete the message and wake up the caller, using the given return code,
> + * or zero to mean ok.
> +*/
> +
> +static inline void nuc900_i2c_master_complete(struct nuc900_i2c *i2c, int ret)
> +{
> +	dev_dbg(i2c->dev, "master_complete %d\n", ret);
> +
> +	i2c->msg_ptr = 0;
> +	i2c->msg = NULL;
> +	i2c->msg_idx++;
> +	i2c->msg_num = 0;
> +	if (ret)
> +		i2c->msg_idx = ret;
> +
> +	wake_up(&i2c->wait);
> +}
> +
> +/* irq enable/disable functions */
> +
> +static inline void nuc900_i2c_disable_irq(struct nuc900_i2c *i2c)
> +{
> +	unsigned long tmp;
> +
> +	tmp = readl(i2c->regs + CSR);
> +	writel(tmp & ~IRQEN, i2c->regs + CSR);
> +}
> +
> +static inline void nuc900_i2c_enable_irq(struct nuc900_i2c *i2c)
> +{
> +	unsigned long tmp;
> +
> +	tmp = readl(i2c->regs + CSR);
> +	writel(tmp | IRQEN, i2c->regs + CSR);
> +}

might be easeir to have an call to set the irq state?

> +
> +/* nuc900_i2c_message_start
> + *
> + * put the start of a message onto the bus
> +*/
> +
> +static void nuc900_i2c_message_start(struct nuc900_i2c *i2c,
> +				      struct i2c_msg *msg)
> +{
> +	unsigned int addr = (msg->addr & 0x7f) << 1;
> +
> +	if (msg->flags & I2C_M_RD)
> +		addr |= 0x1;
> +	writel(addr & 0xff, i2c->regs + TXR);
> +	writel(I2C_CMD_START | I2C_CMD_WRITE, i2c->regs + CMDR);
> +}
> +
> +static inline void nuc900_i2c_stop(struct nuc900_i2c *i2c, int ret)
> +{
> +
> +	dev_dbg(i2c->dev, "STOP\n");
> +
> +	/* stop the transfer */
> +	i2c->state = STATE_STOP;
> +	writel(I2C_CMD_STOP, i2c->regs + CMDR);
> +
> +	nuc900_i2c_master_complete(i2c, ret);
> +	nuc900_i2c_disable_irq(i2c);
> +}
> +
> +/* helper functions to determine the current state in the set of
> + * messages we are sending */
> +
> +/* is_lastmsg()
> + *
> + * returns TRUE if the current message is the last in the set
> +*/
> +
> +static inline int is_lastmsg(struct nuc900_i2c *i2c)
> +{
> +	return i2c->msg_idx >= (i2c->msg_num - 1);
> +}
> +
> +/* is_msglast
> + *
> + * returns TRUE if we this is the last byte in the current message
> +*/
> +
> +static inline int is_msglast(struct nuc900_i2c *i2c)
> +{
> +	return i2c->msg_ptr == i2c->msg->len-1;
> +}
> +
> +/* is_msgend
> + *
> + * returns TRUE if we reached the end of the current message
> +*/
> +
> +static inline int is_msgend(struct nuc900_i2c *i2c)
> +{
> +	return i2c->msg_ptr >= i2c->msg->len;
> +}

maybe we should have a library header for processing i2c messages
like this.

> +/* i2s_s3c_irq_nextbyte
> + *
> + * process an interrupt and work out what to do
> + */
> +
> +static int i2s_nuc900_irq_nextbyte(struct nuc900_i2c *i2c,

not i2s, and doesn't match prototype.

maybe change the docs to kerneldoc style?

> +							unsigned long iicstat)

[snip]

> +/* nuc900_i2c_irq
> + *
> + * top level IRQ servicing routine
> +*/
> +
> +static irqreturn_t nuc900_i2c_irq(int irqno, void *dev_id)
> +{
> +	struct nuc900_i2c *i2c = dev_id;
> +	unsigned long status;
> +
> +	status = readl(i2c->regs + CSR);
> +	writel(status | IRQFLAG, i2c->regs + CSR);
> +
> +	if (status & ARBIT_LOST) {
> +		/* deal with arbitration loss */
> +		dev_err(i2c->dev, "deal with arbitration loss\n");
> +		goto out;
> +	}
> +
> +	if (i2c->state == STATE_IDLE) {
> +		dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
> +		goto out;
> +	}
> +
> +	/* pretty much this leaves us with the fact that we've
> +	 * transmitted or received whatever byte we last sent */
> +
> +	i2s_nuc900_irq_nextbyte(i2c, status);
> +
> + out:
> +	return IRQ_HANDLED;
> +}
> +
> +
> +/* nuc900_i2c_set_master
> + *
> + * get the i2c bus for a master transaction
> +*/
> +
> +static int nuc900_i2c_set_master(struct nuc900_i2c *i2c)
> +{
> +	int timeout = 400;
> +
> +	while (timeout-- > 0) {
> +		if (((readl(i2c->regs + SWR) & I2CSTART) == I2CSTART) &&
> +				((readl(i2c->regs + CSR) & I2CBUSY) == 0)) {
> +			return 0;
> +		}
> +
> +		msleep(1);
> +	}
> +
> +	return -ETIMEDOUT;
> +}
> +
> +/* nuc900_i2c_doxfer
> + *
> + * this starts an i2c transfer
> +*/
> +
> +static int nuc900_i2c_doxfer(struct nuc900_i2c *i2c,
> +			      struct i2c_msg *msgs, int num)
> +{
> +	unsigned long iicstat, timeout;
> +	int spins = 20;
> +	int ret;
> +
> +	ret = nuc900_i2c_set_master(i2c);
> +	if (ret != 0) {
> +		dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
> +		ret = -EAGAIN;
> +		goto out;
> +	}
> +
> +	spin_lock_irq(&i2c->lock);
> +
> +	i2c->msg     = msgs;
> +	i2c->msg_num = num;
> +	i2c->msg_ptr = 0;
> +	i2c->msg_idx = 0;
> +	i2c->state   = STATE_START;
> +
> +	nuc900_i2c_enable_irq(i2c);
> +	nuc900_i2c_message_start(i2c, msgs);
> +	spin_unlock_irq(&i2c->lock);
> +
> +	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
> +
> +	ret = i2c->msg_idx;
> +
> +	/* having these next two as dev_err() makes life very
> +	 * noisy when doing an i2cdetect */
> +
> +	if (timeout == 0)
> +		dev_dbg(i2c->dev, "timeout\n");
> +	else if (ret != num)
> +		dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
> +
> +	/* ensure the stop has been through the bus */
> +
> +	dev_dbg(i2c->dev, "waiting for bus idle\n");
> +
> +	/* first, try busy waiting briefly */
> +	do {
> +		iicstat = readl(i2c->regs + CSR);
> +	} while ((iicstat & I2CBUSY) && --spins);
> +
> +	/* if that timed out sleep */
> +	if (!spins) {
> +		msleep(1);
> +		iicstat = readl(i2c->regs + CSR);
> +	}
> +
> +	if (iicstat & I2CBUSY)
> +		dev_warn(i2c->dev, "timeout waiting for bus idle\n");
> +
> + out:
> +	return ret;
> +}
> +
> +/* nuc900_i2c_xfer
> + *
> + * first port of call from the i2c bus code when an message needs
> + * transferring across the i2c bus.
> +*/
> +
> +static int nuc900_i2c_xfer(struct i2c_adapter *adap,
> +			struct i2c_msg *msgs, int num)
> +{
> +	struct nuc900_i2c *i2c = (struct nuc900_i2c *)adap->algo_data;
> +	int retry;
> +	int ret;
> +
> +	for (retry = 0; retry < adap->retries; retry++) {
> +
> +		ret = nuc900_i2c_doxfer(i2c, msgs, num);
> +
> +		if (ret != -EAGAIN)
> +			return ret;
> +
> +		dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
> +
> +		udelay(100);
> +	}
> +
> +	return -EREMOTEIO;
> +}
> +
> +/* declare our i2c functionality */
> +static u32 nuc900_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
> +}
> +
> +/* i2c bus registration info */
> +
> +static const struct i2c_algorithm nuc900_i2c_algorithm = {
> +	.master_xfer		= nuc900_i2c_xfer,
> +	.functionality		= nuc900_i2c_func,
> +};
> +
> +/* nuc900_i2c_probe
> + *
> + * called by the bus driver when a suitable device is found
> +*/
> +
> +static int __devinit nuc900_i2c_probe(struct platform_device *pdev)
> +{
> +	struct nuc900_i2c *i2c;
> +	struct nuc900_platform_i2c *pdata;
> +	struct resource *res;
> +	unsigned int apbclk_khz;
> +	int ret;
> +
> +	pdata = pdev->dev.platform_data;
> +	if (!pdata) {
> +		dev_err(&pdev->dev, "no platform data\n");
> +		return -EINVAL;
> +	}
> +
> +	i2c = kzalloc(sizeof(struct nuc900_i2c), GFP_KERNEL);
> +	if (!i2c) {
> +		dev_err(&pdev->dev, "no memory for state\n");
> +		return -ENOMEM;
> +	}
> +
> +	strlcpy(i2c->adap.name, "nuc900-i2c0", sizeof(i2c->adap.name));
> +	i2c->adap.owner   = THIS_MODULE;
> +	i2c->adap.algo    = &nuc900_i2c_algorithm;
> +	i2c->adap.retries = 2;
> +	i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;
> +
> +	spin_lock_init(&i2c->lock);
> +	init_waitqueue_head(&i2c->wait);
> +
> +	/* find the clock and enable it */
> +
> +	i2c->dev = &pdev->dev;
> +	i2c->clk = clk_get(&pdev->dev, "nuc900-i2c0");

you really shouldn't need the second argument, the bus clock for
a device should be findable with NULL.

note, fixing the s3c series as soon as possible.

> +	if (IS_ERR(i2c->clk)) {
> +		dev_err(&pdev->dev, "cannot get clock\n");
> +		ret = -ENOENT;
> +		goto err_noclk;
> +	}
> +
> +	dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
> +
> +	clk_enable(i2c->clk);
> +
> +	/* map the registers */
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (res == NULL) {
> +		dev_err(&pdev->dev, "cannot find IO resource\n");
> +		ret = -ENOENT;
> +		goto err_clk;
> +	}
> +
> +	i2c->ioarea = request_mem_region(res->start, resource_size(res),
> +					 pdev->name);
> +
> +	if (i2c->ioarea == NULL) {
> +		dev_err(&pdev->dev, "cannot request IO\n");
> +		ret = -ENXIO;
> +		goto err_clk;
> +	}
> +
> +	i2c->regs = ioremap(res->start, resource_size(res));
> +
> +	if (i2c->regs == NULL) {
> +		dev_err(&pdev->dev, "cannot map IO\n");
> +		ret = -ENXIO;
> +		goto err_ioarea;
> +	}
> +
> +	dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
> +		i2c->regs, i2c->ioarea, res);
> +
> +	/* setup info block for the i2c core */
> +
> +	i2c->adap.algo_data = i2c;
> +	i2c->adap.dev.parent = &pdev->dev;
> +
> +	mfp_set_groupg(&pdev->dev);
> +
> +	pdata->get_clock(NULL, NULL, &apbclk_khz);

clk_get_rate() should be used here.

> +	ret = apbclk_khz/(pdata->bus_freq * 5) - 1;
> +	writel(ret & 0xffff, i2c->regs + DIVIDER);
> +
> +	/* find the IRQ for this unit (note, this relies on the init call to
> +	 * ensure no current IRQs pending
> +	 */
> +
> +	i2c->irq = ret = platform_get_irq(pdev, 0);
> +	if (ret <= 0) {
> +		dev_err(&pdev->dev, "cannot find IRQ\n");
> +		goto err_iomap;
> +	}
> +
> +	ret = request_irq(i2c->irq, nuc900_i2c_irq, IRQF_DISABLED,
> +			  dev_name(&pdev->dev), i2c);

do you really want to run this with all irqs disabled?

> +	if (ret != 0) {
> +		dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
> +		goto err_iomap;
> +	}
> +
> +	/* Note, previous versions of the driver used i2c_add_adapter()
> +	 * to add the bus at any number. We now pass the bus number via
> +	 * the platform data, so if unset it will now default to always
> +	 * being bus 0.
> +	 */
> +
> +	i2c->adap.nr = pdata->bus_num;
> +
> +	ret = i2c_add_numbered_adapter(&i2c->adap);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
> +		goto err_irq;
> +	}
> +
> +	platform_set_drvdata(pdev, i2c);
> +
> +	dev_info(&pdev->dev, "%s: NUC900 I2C adapter\n",
> +						dev_name(&i2c->adap.dev));
> +	return 0;
> +
> + err_irq:
> +	free_irq(i2c->irq, i2c);
> +
> + err_iomap:
> +	iounmap(i2c->regs);
> +
> + err_ioarea:
> +	release_resource(i2c->ioarea);
> +	kfree(i2c->ioarea);
> +
> + err_clk:
> +	clk_disable(i2c->clk);
> +	clk_put(i2c->clk);
> +
> + err_noclk:
> +	kfree(i2c);
> +	return ret;
> +}
> +
> +/* nuc900_i2c_remove
> + *
> + * called when device is removed from the bus
> +*/
> +
> +static int __devexit nuc900_i2c_remove(struct platform_device *pdev)
> +{
> +	struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
> +
> +	i2c_del_adapter(&i2c->adap);
> +	free_irq(i2c->irq, i2c);
> +
> +	clk_disable(i2c->clk);
> +	clk_put(i2c->clk);
> +
> +	iounmap(i2c->regs);
> +
> +	release_resource(i2c->ioarea);
> +	kfree(i2c->ioarea);
> +	kfree(i2c);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver nuc900_i2c_driver = {
> +	.probe		= nuc900_i2c_probe,
> +	.remove		= __devexit_p(nuc900_i2c_remove),
> +	.driver		= {
> +		.owner	= THIS_MODULE,
> +		.name	= "nuc900-i2c0",
> +	},
> +};
> +
> +static int __init i2c_adap_nuc900_init(void)
> +{
> +	return platform_driver_register(&nuc900_i2c_driver);
> +}
> +
> +static void __exit i2c_adap_nuc900_exit(void)
> +{
> +	platform_driver_unregister(&nuc900_i2c_driver);
> +}
> +subsys_initcall(i2c_adap_nuc900_init);
> +module_exit(i2c_adap_nuc900_exit);
> +
> +MODULE_DESCRIPTION("NUC900 I2C Bus driver");
> +MODULE_AUTHOR("Wan ZongShun, <[email-masked]>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:nuc900-i2c0");

-- 
Ben (ben at fluff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'