On Fri, Jul 13, 2012 at 12:09:01PM +0530, Jayachandran C wrote:
> From: Ganesan Ramalingam <ganesanr@xxxxxxxxxxxx>
>
> Deprecate 'regstep' property and use the standard 'reg-shift' property
> for register offset shifts. 'regstep' will still be supported as an
> optional property, but will give a warning when used.
>
> Signed-off-by: Ganesan Ramalingam <ganesanr@xxxxxxxxxxxx>
> Signed-off-by: Jayachandran C <jayachandranc@xxxxxxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/i2c/i2c-ocores.txt | 8 +++-
> drivers/i2c/busses/i2c-ocores.c | 39 ++++++++++++--------
> include/linux/i2c-ocores.h | 2 +-
> 3 files changed, 31 insertions(+), 18 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> index bfec894..1c9334b 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> @@ -4,11 +4,14 @@ Required properties:
> - compatible : "opencores,i2c-ocores"
> - reg : bus address start and address range size of device
> - interrupts : interrupt number
> -- regstep : size of device registers in bytes
> - clock-frequency : frequency of bus clock in Hz
> - #address-cells : should be <1>
> - #size-cells : should be <0>
>
> +Optional properties:
> +- reg-shift : device register offsets are shifted by this value
> +- regstep : deprecated, use reg-shift above
> +
> Example:
>
> i2c0: ocores@a0000000 {
> @@ -17,9 +20,10 @@ Example:
> compatible = "opencores,i2c-ocores";
> reg = <0xa0000000 0x8>;
> interrupts = <10>;
> - regstep = <1>;
> clock-frequency = <20000000>;
>
> + reg-shift = <0>; /* 8 bit registers */
> +
> dummy@60 {
> compatible = "dummy";
> reg = <0x60>;
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index e8159db..fb8db30 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -25,10 +25,11 @@
> #include <linux/slab.h>
> #include <linux/io.h>
> #include <linux/of_i2c.h>
> +#include <linux/log2.h>
>
> struct ocores_i2c {
> void __iomem *base;
> - int regstep;
> + int reg_shift;
> wait_queue_head_t wait;
> struct i2c_adapter adap;
> struct i2c_msg *msg;
> @@ -71,12 +72,12 @@ struct ocores_i2c {
>
> static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
> {
> - iowrite8(value, i2c->base + reg * i2c->regstep);
> + iowrite8(value, i2c->base + (reg << i2c->reg_shift));
> }
>
> static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
> {
> - return ioread8(i2c->base + reg * i2c->regstep);
> + return ioread8(i2c->base + (reg << i2c->reg_shift));
> }
>
> static void ocores_process(struct ocores_i2c *i2c)
> @@ -219,22 +220,30 @@ static struct i2c_adapter ocores_adapter = {
> static int ocores_i2c_of_probe(struct platform_device *pdev,
> struct ocores_i2c *i2c)
> {
> - const __be32* val;
> -
> - val = of_get_property(pdev->dev.of_node, "regstep", NULL);
> - if (!val) {
> - dev_err(&pdev->dev, "Missing required parameter 'regstep'\n");
> - return -ENODEV;
> - }
> - i2c->regstep = be32_to_cpup(val);
> + struct device_node *np = pdev->dev.of_node;
> + u32 val;
> +
> + if (of_property_read_u32(np, "reg-shift", &val)) {
> + /* no 'reg-shift', check for deprecated 'regstep' */
> + if (!of_property_read_u32(np, "regstep", &val)) {
> + if (!is_power_of_2(val)) {
> + dev_err(&pdev->dev, "invalid regstep %d\n",
> + val);
> + return -EINVAL;
> + }
> + i2c->reg_shift = ilog2(val);
> + dev_warn(&pdev->dev,
> + "regstep property deprecated, use reg-shift\n");
> + }
> + } else
> + i2c->reg_shift = val;
Now you are assigning an u32 to an int. Regstep will never be really a
huge number, but still...
Also, braces around else-block according to coding style.
>
> - val = of_get_property(pdev->dev.of_node, "clock-frequency", NULL);
> - if (!val) {
> + if (of_property_read_u32(np, "clock-frequency", &val)) {
> dev_err(&pdev->dev,
> "Missing required parameter 'clock-frequency'\n");
> return -ENODEV;
> }
> - i2c->clock_khz = be32_to_cpup(val) / 1000;
> + i2c->clock_khz = val / 1000;
Okay, "/ 1000" will guarantee that the divided value will fit into an
int. Yet, what do we gain by not using u32?
Regards,
Wolfram
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