Commit 5ae5b113 authored by Chaithrika U S's avatar Chaithrika U S Committed by Kevin Hilman
Browse files

i2c: davinci: Add helper functions for power management 



Add i2c reset control and clock divider calculation functions
which will be useful for power management features.

Signed-off-by: default avatarChaithrika U S <chaithrika@ti.com>
Acked-by: default avatarKevin Hilman <khilman@deeprootsystems.com>
parent c062a251

drivers/i2c/busses/i2c-davinci.c

+37 −19
Original line number Diff line number Diff line
@@ -126,12 +126,21 @@ 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;
@@ -140,15 +149,6 @@ 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
@@ -180,12 +180,32 @@ 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",
@@ -196,9 +216,7 @@ 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);