Commit 9446f62e authored by Noralf Trønnes's avatar Noralf Trønnes Committed by Wolfram Sang
Browse files

i2c: bcm2835: Add support for dynamic clock 



Support a dynamic clock by reading the frequency and setting the
divisor in the transfer function instead of during probe.

Signed-off-by: default avatarNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: default avatarMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent e13e19e1

drivers/i2c/busses/i2c-bcm2835.c

+32 −19
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ struct bcm2835_i2c_dev { 
	void __iomem *regs;

	struct clk *clk;

	int irq;

	u32 bus_clk_rate;

	struct i2c_adapter adapter;

	struct completion completion;

	struct i2c_msg *curr_msg;
@@ -78,6 +79,30 @@ static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) 
	return readl(i2c_dev->regs + reg);

}



static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev)

{

	u32 divider;



	divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk),

			       i2c_dev->bus_clk_rate);

	/*

	 * Per the datasheet, the register is always interpreted as an even

	 * number, by rounding down. In other words, the LSB is ignored. So,

	 * if the LSB is set, increment the divider to avoid any issue.

	 */

	if (divider & 1)

		divider++;

	if ((divider < BCM2835_I2C_CDIV_MIN) ||

	    (divider > BCM2835_I2C_CDIV_MAX)) {

		dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n");

		return -EINVAL;

	}



	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);



	return 0;

}



static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)

{

	u32 val;
@@ -224,7 +249,7 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], 
{

	struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);

	unsigned long time_left;

	int i;

	int i, ret;



	for (i = 0; i < (num - 1); i++)

		if (msgs[i].flags & I2C_M_RD) {
@@ -233,6 +258,10 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], 
			return -EOPNOTSUPP;

		}



	ret = bcm2835_i2c_set_divider(i2c_dev);

	if (ret)

		return ret;



	i2c_dev->curr_msg = msgs;

	i2c_dev->num_msgs = num;

	reinit_completion(&i2c_dev->completion);
@@ -282,7 +311,6 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) 
{

	struct bcm2835_i2c_dev *i2c_dev;

	struct resource *mem, *irq;

	u32 bus_clk_rate, divider;

	int ret;

	struct i2c_adapter *adap;
@@ -306,28 +334,13 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) 
	}



	ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",

				   &bus_clk_rate);

				   &i2c_dev->bus_clk_rate);

	if (ret < 0) {

		dev_warn(&pdev->dev,

			 "Could not read clock-frequency property\n");

		bus_clk_rate = 100000;

		i2c_dev->bus_clk_rate = 100000;

	}



	divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate);

	/*

	 * Per the datasheet, the register is always interpreted as an even

	 * number, by rounding down. In other words, the LSB is ignored. So,

	 * if the LSB is set, increment the divider to avoid any issue.

	 */

	if (divider & 1)

		divider++;

	if ((divider < BCM2835_I2C_CDIV_MIN) ||

	    (divider > BCM2835_I2C_CDIV_MAX)) {

		dev_err(&pdev->dev, "Invalid clock-frequency\n");

		return -ENODEV;

	}

	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);



	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

	if (!irq) {

		dev_err(&pdev->dev, "No IRQ resource\n");