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Commit b61d1575 authored by Andrew Lunn's avatar Andrew Lunn Committed by Wolfram Sang
Browse files

I2C: MV64XYZ: Add Device Tree support 



Extends the driver to get properties from device tree. Rather than
pass the N & M factors in DT, use the more standard clock-frequency
property. Calculate N & M at run time. In order to do this, we need to
know tclk. So the driver uses clk_get() etc in order to get the clock
and clk_get_rate() to determine the tclk rate. Not all platforms
however have CLK, so some #ifdefery is needed to ensure the driver
still compiles when CLK is not available.

Signed-off-by: default avatarAndrew Lunn <andrew@lunn.ch>

[wsa: converted some ints to u32 to match signedness]

Signed-off-by: default avatarWolfram Sang <w.sang@pengutronix.de>
parent 6f535b94

Documentation/devicetree/bindings/i2c/mrvl-i2c.txt

+18 −1
Original line number Diff line number Diff line 
* I2C

* Marvell MMP I2C controller



Required properties :
@@ -32,3 +32,20 @@ Examples: 
		interrupts = <58>;

	};



* Marvell MV64XXX I2C controller



Required properties :



 - reg             : Offset and length of the register set for the device

 - compatible      : Should be "marvell,mv64xxx-i2c"

 - interrupts      : The interrupt number

 - clock-frequency : Desired I2C bus clock frequency in Hz.



Examples:



	i2c@11000 {

		compatible = "marvell,mv64xxx-i2c";

		reg = <0x11000 0x20>;

		interrupts = <29>;

		clock-frequency = <100000>;

	};

drivers/i2c/busses/i2c-mv64xxx.c

+128 −5
Original line number Diff line number Diff line
@@ -18,6 +18,11 @@ 
#include <linux/mv643xx_i2c.h>

#include <linux/platform_device.h>

#include <linux/io.h>

#include <linux/of.h>

#include <linux/of_irq.h>

#include <linux/of_i2c.h>

#include <linux/clk.h>

#include <linux/err.h>



/* Register defines */

#define	MV64XXX_I2C_REG_SLAVE_ADDR			0x00
@@ -98,6 +103,9 @@ struct mv64xxx_i2c_data { 
	int			rc;

	u32			freq_m;

	u32			freq_n;

#if defined(CONFIG_HAVE_CLK)

	struct clk              *clk;

#endif

	wait_queue_head_t	waitq;

	spinlock_t		lock;

	struct i2c_msg		*msg;
@@ -521,6 +529,82 @@ mv64xxx_i2c_unmap_regs(struct mv64xxx_i2c_data *drv_data) 
	drv_data->reg_base_p = 0;

}



#ifdef CONFIG_OF

static int __devinit

mv64xxx_calc_freq(const int tclk, const int n, const int m)

{

	return tclk / (10 * (m + 1) * (2 << n));

}



static bool __devinit

mv64xxx_find_baud_factors(const u32 req_freq, const u32 tclk, u32 *best_n,

			  u32 *best_m)

{

	int freq, delta, best_delta = INT_MAX;

	int m, n;



	for (n = 0; n <= 7; n++)

		for (m = 0; m <= 15; m++) {

			freq = mv64xxx_calc_freq(tclk, n, m);

			delta = req_freq - freq;

			if (delta >= 0 && delta < best_delta) {

				*best_m = m;

				*best_n = n;

				best_delta = delta;

			}

			if (best_delta == 0)

				return true;

		}

	if (best_delta == INT_MAX)

		return false;

	return true;

}



static int __devinit

mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,

		  struct device_node *np)

{

	u32 bus_freq, tclk;

	int rc = 0;



	/* CLK is mandatory when using DT to describe the i2c bus. We

	 * need to know tclk in order to calculate bus clock

	 * factors.

	 */

#if !defined(CONFIG_HAVE_CLK)

	/* Have OF but no CLK */

	return -ENODEV;

#else

	if (IS_ERR(drv_data->clk)) {

		rc = -ENODEV;

		goto out;

	}

	tclk = clk_get_rate(drv_data->clk);

	of_property_read_u32(np, "clock-frequency", &bus_freq);

	if (!mv64xxx_find_baud_factors(bus_freq, tclk,

				       &drv_data->freq_n, &drv_data->freq_m)) {

		rc = -EINVAL;

		goto out;

	}

	drv_data->irq = irq_of_parse_and_map(np, 0);



	/* Its not yet defined how timeouts will be specified in device tree.

	 * So hard code the value to 1 second.

	 */

	drv_data->adapter.timeout = HZ;

out:

	return rc;

#endif

}

#else /* CONFIG_OF */

static int __devinit

mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,

		  struct device_node *np)

{

	return -ENODEV;

}

#endif /* CONFIG_OF */



static int __devinit

mv64xxx_i2c_probe(struct platform_device *pd)

{
@@ -528,7 +612,7 @@ mv64xxx_i2c_probe(struct platform_device *pd) 
	struct mv64xxx_i2c_pdata	*pdata = pd->dev.platform_data;

	int	rc;



	if (!pdata)

	if ((!pdata && !pd->dev.of_node))

		return -ENODEV;



	drv_data = kzalloc(sizeof(struct mv64xxx_i2c_data), GFP_KERNEL);
@@ -546,19 +630,35 @@ mv64xxx_i2c_probe(struct platform_device *pd) 
	init_waitqueue_head(&drv_data->waitq);

	spin_lock_init(&drv_data->lock);



#if defined(CONFIG_HAVE_CLK)

	/* Not all platforms have a clk */

	drv_data->clk = clk_get(&pd->dev, NULL);

	if (!IS_ERR(drv_data->clk)) {

		clk_prepare(drv_data->clk);

		clk_enable(drv_data->clk);

	}

#endif

	if (pdata) {

		drv_data->freq_m = pdata->freq_m;

		drv_data->freq_n = pdata->freq_n;

		drv_data->irq = platform_get_irq(pd, 0);

		drv_data->adapter.timeout = msecs_to_jiffies(pdata->timeout);

	} else if (pd->dev.of_node) {

		rc = mv64xxx_of_config(drv_data, pd->dev.of_node);

		if (rc)

			goto exit_unmap_regs;

	}

	if (drv_data->irq < 0) {

		rc = -ENXIO;

		goto exit_unmap_regs;

	}



	drv_data->adapter.dev.parent = &pd->dev;

	drv_data->adapter.algo = &mv64xxx_i2c_algo;

	drv_data->adapter.owner = THIS_MODULE;

	drv_data->adapter.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;

	drv_data->adapter.timeout = msecs_to_jiffies(pdata->timeout);

	drv_data->adapter.nr = pd->id;

	drv_data->adapter.dev.of_node = pd->dev.of_node;

	platform_set_drvdata(pd, drv_data);

	i2c_set_adapdata(&drv_data->adapter, drv_data);
@@ -577,11 +677,20 @@ mv64xxx_i2c_probe(struct platform_device *pd) 
		goto exit_free_irq;

	}



	of_i2c_register_devices(&drv_data->adapter);



	return 0;



	exit_free_irq:

		free_irq(drv_data->irq, drv_data);

	exit_unmap_regs:

#if defined(CONFIG_HAVE_CLK)

	/* Not all platforms have a clk */

	if (!IS_ERR(drv_data->clk)) {

		clk_disable(drv_data->clk);

		clk_unprepare(drv_data->clk);

	}

#endif

		mv64xxx_i2c_unmap_regs(drv_data);

	exit_kfree:

		kfree(drv_data);
@@ -597,17 +706,31 @@ mv64xxx_i2c_remove(struct platform_device *dev) 
	rc = i2c_del_adapter(&drv_data->adapter);

	free_irq(drv_data->irq, drv_data);

	mv64xxx_i2c_unmap_regs(drv_data);

#if defined(CONFIG_HAVE_CLK)

	/* Not all platforms have a clk */

	if (!IS_ERR(drv_data->clk)) {

		clk_disable(drv_data->clk);

		clk_unprepare(drv_data->clk);

	}

#endif

	kfree(drv_data);



	return rc;

}



static const struct of_device_id mv64xxx_i2c_of_match_table[] __devinitdata = {

	{ .compatible = "marvell,mv64xxx-i2c", },

	{}

};

MODULE_DEVICE_TABLE(of, mv64xxx_i2c_of_match_table);



static struct platform_driver mv64xxx_i2c_driver = {

	.probe	= mv64xxx_i2c_probe,

	.remove	= __devexit_p(mv64xxx_i2c_remove),

	.driver	= {

		.owner	= THIS_MODULE,

		.name	= MV64XXX_I2C_CTLR_NAME,

		.of_match_table = of_match_ptr(mv64xxx_i2c_of_match_table),

	},

};