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Subject[PATCH v2 2/4] i2c: davinci: Add helper functions
Date
Add i2c reset control and clock divider calculation functions
which will be useful for power management features.

Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
drivers/i2c/busses/i2c-davinci.c | 56 +++++++++++++++++++++++++-------------
1 files changed, 37 insertions(+), 19 deletions(-)
diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index 44a3cb3..81c1049 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -124,12 +124,21 @@ static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg)
return __raw_readw(i2c_dev->base + reg);
}

-/*
- * This functions configures I2C and brings I2C out of reset.
- * This function is called during I2C init function. This function
- * also gets called if I2C encounters any errors.
- */
-static int i2c_davinci_init(struct davinci_i2c_dev *dev)
+static inline void davinci_i2c_reset_ctrl(struct davinci_i2c_dev *i2c_dev,
+ int val)
+{
+ u16 w;
+
+ w = davinci_i2c_read_reg(i2c_dev, DAVINCI_I2C_MDR_REG);
+ if (!val) /* put I2C into reset */
+ w &= ~DAVINCI_I2C_MDR_IRS;
+ else /* take I2C out of reset */
+ w |= DAVINCI_I2C_MDR_IRS;
+
+ davinci_i2c_write_reg(i2c_dev, DAVINCI_I2C_MDR_REG, w);
+}
+
+static void i2c_davinci_calc_clk_dividers(struct davinci_i2c_dev *dev)
{
struct davinci_i2c_platform_data *pdata = dev->dev->platform_data;
u16 psc;
@@ -138,15 +147,6 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
u32 clkh;
u32 clkl;
u32 input_clock = clk_get_rate(dev->clk);
- u16 w;
-
- if (!pdata)
- pdata = &davinci_i2c_platform_data_default;
-
- /* put I2C into reset */
- w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
- w &= ~DAVINCI_I2C_MDR_IRS;
- davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);

/* NOTE: I2C Clock divider programming info
* As per I2C specs the following formulas provide prescaler
@@ -178,12 +178,32 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
davinci_i2c_write_reg(dev, DAVINCI_I2C_CLKH_REG, clkh);
davinci_i2c_write_reg(dev, DAVINCI_I2C_CLKL_REG, clkl);

+ dev_dbg(dev->dev, "input_clock = %d, CLK = %d\n", input_clock, clk);
+}
+
+/*
+ * This function configures I2C and brings I2C out of reset.
+ * This function is called during I2C init function. This function
+ * also gets called if I2C encounters any errors.
+ */
+static int i2c_davinci_init(struct davinci_i2c_dev *dev)
+{
+ struct davinci_i2c_platform_data *pdata = dev->dev->platform_data;
+
+ if (!pdata)
+ pdata = &davinci_i2c_platform_data_default;
+
+ /* put I2C into reset */
+ davinci_i2c_reset_ctrl(dev, 0);
+
+ /* compute clock dividers */
+ i2c_davinci_calc_clk_dividers(dev);
+
/* Respond at reserved "SMBus Host" slave address" (and zero);
* we seem to have no option to not respond...
*/
davinci_i2c_write_reg(dev, DAVINCI_I2C_OAR_REG, 0x08);

- dev_dbg(dev->dev, "input_clock = %d, CLK = %d\n", input_clock, clk);
dev_dbg(dev->dev, "PSC = %d\n",
davinci_i2c_read_reg(dev, DAVINCI_I2C_PSC_REG));
dev_dbg(dev->dev, "CLKL = %d\n",
@@ -194,9 +214,7 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
pdata->bus_freq, pdata->bus_delay);

/* Take the I2C module out of reset: */
- w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
- w |= DAVINCI_I2C_MDR_IRS;
- davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
+ davinci_i2c_reset_ctrl(dev, 1);

/* Enable interrupts */
davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, I2C_DAVINCI_INTR_ALL);
--
1.5.6


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