[PATCH 1/2] i2c: s3c24xx: Add device tree support
Grant Likely
grant.likely at secretlab.ca
Mon Jul 18 14:28:59 EST 2011
On Mon, Jul 18, 2011 at 06:20:40AM +0530, Thomas Abraham wrote:
> Add device tree support for Samsung's s3c24xx i2c driver. It adds
> support for parsing platform data from device tree and initialize
> all the slave devices specified as child nodes.
>
> Signed-off-by: Thomas Abraham <thomas.abraham at linaro.org>
> ---
> .../devicetree/bindings/i2c/samsung-i2c.txt | 43 ++++++++++
> drivers/i2c/busses/i2c-s3c2410.c | 87 ++++++++++++++++----
> 2 files changed, 115 insertions(+), 15 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/i2c/samsung-i2c.txt
>
> diff --git a/Documentation/devicetree/bindings/i2c/samsung-i2c.txt b/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> new file mode 100644
> index 0000000..73191c3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> @@ -0,0 +1,43 @@
> +* Samsung's I2C controller
> +
> +The Samsung's I2C controller is used to interface with I2C devices.
> +
> +Required properties:
> + - compatible: value should be either of the following.
> + (a) "samsung, s3c2410-i2c", for i2c compatible with s3c2410 i2c.
> + (b) "samsung, s3c2440-i2c", for i2c compatible with s3c2440 i2c.
> +
> + - reg: physical base address of the controller and length of memory mapped
> + region.
> +
> + - interrupts : interrupt number to the cpu.
> +
> + - samsung,i2c-bus-number: Specifies the i2c bus number.
Drop this property. i2c bus numbers are dynamically assigned when
using the DT.
> +
> + - samsung,i2c-sda-delay: Delay (in ns) applied to data line (SDA) edges.
> +
> +Optional properties:
> + - samsung,i2c-slave-addr: Slave address in multi-master enviroment. If not
> + specified, default value is 0x10.
> +
> + - samsung,i2c-max-bus-freq: Desired frequency in Hz of the bus. If not
> + specified, the default value in Hz is 100000.
> +
> +Example:
> +
> + i2c at 13870000 {
> + compatible = "samsung,s3c2440-i2c";
> + reg = <0x13870000 0x100>;
> + interrupts = <345>;
> + samsung,i2c-bus-number = <1>;
> + samsung,i2c-slave-addr = <16>;
> + samsung,i2c-sda-delay = <100>;
> + samsung,i2c-max-bus-freq = <100000>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + wm8994 at 1a {
> + compatible = "wlf,wm8994";
> + reg = <0x1a>;
> + };
> + };
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index 6c00c10..5a84a0b 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -35,6 +35,9 @@
> #include <linux/cpufreq.h>
> #include <linux/slab.h>
> #include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_i2c.h>
> +#include <linux/of_device.h>
>
> #include <asm/irq.h>
>
> @@ -83,6 +86,33 @@ struct s3c24xx_i2c {
> #endif
> };
>
> +#ifdef CONFIG_OF
> +static enum s3c24xx_i2c_type samsung_i2c_types[] = {
> + TYPE_S3C2410,
> + TYPE_S3C2440
> +};
> +
> +static const struct of_device_id s3c24xx_i2c_match[] = {
> + { .compatible = "samsung,s3c2410-i2c", .data = &samsung_i2c_types[0], },
> + { .compatible = "samsung,s3c2440-i2c", .data = &samsung_i2c_types[1], },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
The samsung_i2c_types[] array is unnecessary. You can simply do:
static const struct of_device_id s3c24xx_i2c_match[] = {
{ .compatible = "samsung,s3c2410-i2c", .data = (void*)TYPE_S3C2410, },
{ .compatible = "samsung,s3c2440-i2c", .data = (void*)TYPE_S3C2440, },
{},
};
MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
Or, drop the .data field entirely and call of_device_is_compatible()
directly in s3c24xx_i2c_is2440().
> +
> +static const struct
> +of_device_id *s3c24xx_i2c_get_of_device_id(struct platform_device *pdev)
> +{
> + return of_match_device(s3c24xx_i2c_match, &pdev->dev);
> +}
> +#else
> +#define s3c24xx_i2c_match NULL
> +static const struct
> +of_device_id *s3c24xx_i2c_get_of_device_id(struct platform_device *pdev)
> +{
> + return NULL;
> +}
> +#endif
> +
> /* default platform data removed, dev should always carry data. */
>
> /* s3c24xx_i2c_is2440()
> @@ -93,9 +123,15 @@ struct s3c24xx_i2c {
> static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
> {
> struct platform_device *pdev = to_platform_device(i2c->dev);
> + const struct of_device_id *i2c_of_id;
> enum s3c24xx_i2c_type type;
>
> - type = platform_get_device_id(pdev)->driver_data;
> + i2c_of_id = s3c24xx_i2c_get_of_device_id(pdev);
> + if (platform_get_device_id(pdev))
> + type = platform_get_device_id(pdev)->driver_data;
> + else
> + type = *(enum s3c24xx_i2c_type *)i2c_of_id->data;
> +
> return type == TYPE_S3C2440;
In fact, most of these line changes go away by putting the folowing
lines above the platform_get_device_id() line:
> }
>
> @@ -630,16 +666,21 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
> unsigned long clkin = clk_get_rate(i2c->clk);
> unsigned int divs, div1;
> unsigned long target_frequency;
> + unsigned int max_freq = 0;
> u32 iiccon;
> int freq;
>
> i2c->clkrate = clkin;
> clkin /= 1000; /* clkin now in KHz */
>
> - dev_dbg(i2c->dev, "pdata desired frequency %lu\n", pdata->frequency);
> -
> - target_frequency = pdata->frequency ? pdata->frequency : 100000;
> + if (i2c->dev->of_node)
> + of_property_read_u32(i2c->dev->of_node,
> + "samsung,i2c-max-bus-freq", &max_freq);
No need to test for i2c->dev->of_node. of_property_read_u32() will
fail gracefully and not modify max_freq if of_node is NULL.
> + else
> + max_freq = pdata->frequency;
When using the DT, the driver needs to make sure pdata is valid before
dereferencing it.
> + dev_dbg(i2c->dev, "desired frequency %u\n", max_freq);
>
> + target_frequency = max_freq ? max_freq : 100000;
> target_frequency /= 1000; /* Target frequency now in KHz */
>
> freq = s3c24xx_i2c_calcdivisor(clkin, target_frequency, &div1, &divs);
> @@ -663,19 +704,24 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
> writel(iiccon, i2c->regs + S3C2410_IICCON);
>
> if (s3c24xx_i2c_is2440(i2c)) {
> - unsigned long sda_delay;
> + unsigned int sda_delay = 0;
Are you sure that a 32bit integer will be able to hold the sda_delay
value? Was there a reason it was an unsigned long in the first place?
>
> - if (pdata->sda_delay) {
> - sda_delay = clkin * pdata->sda_delay;
> + if (i2c->dev->of_node)
> + of_property_read_u32(i2c->dev->of_node,
> + "samsung,i2c-sda-delay", &sda_delay);
sda_delay must be a u32, not an unsigned int.
> + else
> + sda_delay = pdata->sda_delay;
> +
> + if (sda_delay) {
> + sda_delay *= clkin;
> sda_delay = DIV_ROUND_UP(sda_delay, 1000000);
> sda_delay = DIV_ROUND_UP(sda_delay, 5);
> if (sda_delay > 3)
> sda_delay = 3;
> sda_delay |= S3C2410_IICLC_FILTER_ON;
> - } else
> - sda_delay = 0;
> + }
>
> - dev_dbg(i2c->dev, "IICLC=%08lx\n", sda_delay);
> + dev_dbg(i2c->dev, "IICLC=%08x\n", sda_delay);
> writel(sda_delay, i2c->regs + S3C2440_IICLC);
> }
>
> @@ -751,7 +797,7 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
> {
> unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
> struct s3c2410_platform_i2c *pdata;
> - unsigned int freq;
> + unsigned int freq, slave_addr = 0x10;
>
> /* get the plafrom data */
>
> @@ -763,10 +809,14 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
> pdata->cfg_gpio(to_platform_device(i2c->dev));
>
> /* write slave address */
> + if (i2c->dev->of_node)
> + of_property_read_u32(i2c->dev->of_node,
> + "samsung,i2c-slave-addr", &slave_addr);
> + else
> + slave_addr = pdata->slave_addr;
> + writeb(slave_addr, i2c->regs + S3C2410_IICADD);
>
> - writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);
> -
> - dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);
> + dev_info(i2c->dev, "slave address 0x%02x\n", slave_addr);
>
> writel(iicon, i2c->regs + S3C2410_IICCON);
>
> @@ -904,7 +954,12 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
> * being bus 0.
> */
>
> - i2c->adap.nr = pdata->bus_num;
> + if (i2c->dev->of_node)
> + of_property_read_u32(i2c->dev->of_node,
> + "samsung,i2c-bus-number", &i2c->adap.nr);
> + else
> + i2c->adap.nr = pdata->bus_num;
Overall, this patch ends up being quite invasive. You should refactor
to a separate function just for decoding device tree data, and
using it to populate a platform_data structure. Then the patch
doesn't need to touch most of the existing platform_data code, and in
fact makes use of it.
One warning though, be careful to *not* modify the existing
pdev->dev.platform_data pointer. If the driver needs to access
platform_data after probe() returns, then it will need to keep a copy
of it in the driver private data structure.
g.
> + i2c->adap.dev.of_node = pdev->dev.of_node;
>
> ret = i2c_add_numbered_adapter(&i2c->adap);
> if (ret < 0) {
> @@ -912,6 +967,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
> goto err_cpufreq;
> }
>
> + of_i2c_register_devices(&i2c->adap);
> platform_set_drvdata(pdev, i2c);
>
> dev_info(&pdev->dev, "%s: S3C I2C adapter\n", dev_name(&i2c->adap.dev));
> @@ -1021,6 +1077,7 @@ static struct platform_driver s3c24xx_i2c_driver = {
> .owner = THIS_MODULE,
> .name = "s3c-i2c",
> .pm = S3C24XX_DEV_PM_OPS,
> + .of_match_table = s3c24xx_i2c_match,
> },
> };
>
> --
> 1.7.1
>
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