Re: [PATCH v3 2/4] i2c: i2c-ocores: Use reg-shift property

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On 7/13/2012 7:14 PM, 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                    |   36 ++++++++++++--------
  include/linux/i2c-ocores.h                         |    2 +-
  3 files changed, 29 insertions(+), 17 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..721ead9 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;
+	u32 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 +220,29 @@ 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;
+	struct device_node *np = pdev->dev.of_node;
+	u32 val;
+
+	if (of_property_read_u32(np, "reg-shift",&i2c->reg_shift)) {
+		/* 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");
+		}
  	}
-	i2c->regstep = be32_to_cpup(val);

-	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;

  	return 0;
  }
@@ -277,7 +285,7 @@ static int __devinit ocores_i2c_probe(struct platform_device *pdev)

  	pdata = pdev->dev.platform_data;
  	if (pdata) {
-		i2c->regstep = pdata->regstep;
+		i2c->reg_shift = pdata->reg_shift;
  		i2c->clock_khz = pdata->clock_khz;
  	} else {
  		ret = ocores_i2c_of_probe(pdev, i2c);
diff --git a/include/linux/i2c-ocores.h b/include/linux/i2c-ocores.h
index 4d5e57f..5d95df2 100644
--- a/include/linux/i2c-ocores.h
+++ b/include/linux/i2c-ocores.h
@@ -12,7 +12,7 @@
  #define _LINUX_I2C_OCORES_H

  struct ocores_i2c_platform_data {
-	u32 regstep;   /* distance between registers */
+	u32 reg_shift; /* register offset shift value */
  	u32 clock_khz; /* input clock in kHz */
  	u8 num_devices; /* number of devices in the devices list */
  	struct i2c_board_info const *devices; /* devices connected to the bus */

Reviewed By: Rajeev Kumar <rajeev-dlh.kumar@xxxxxx>
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