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i2c: busses: i2c-bcm2835: limits cdiv to allowed values

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Checks if the cdiv value is in between min (0x2) and max (0xFFFE)
supported values by the bcm2835. If not, it returns -ENODEV.

See page 33/34 of BCM2835-ARM-Peripherals.pdf for the DIV register.
https://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf

Signed-off-by: Silvan Wicki <linux_wi@tinag.ch>
[wsa: resolved a merge conflict]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Silvan Wicki 2015-06-18 11:10:11 +02:00 committed by Wolfram Sang
parent 365322fb32
commit a294aba164
1 changed files with 8 additions and 0 deletions
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8
drivers/i2c/busses/i2c-bcm2835.c
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@ -52,6 +52,9 @@
#define BCM2835_I2C_BITMSK_S 0x03FF
#define BCM2835_I2C_CDIV_MIN 0x0002
#define BCM2835_I2C_CDIV_MAX 0xFFFE
#define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000))
struct bcm2835_i2c_dev {
@ -261,6 +264,11 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
*/
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);