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Commit 71531f55 authored by Alexander Shiyan's avatar Alexander Shiyan Committed by Greg Kroah-Hartman
Browse files

w1: mxc_w1: Add warning for base frequency calculation 



Base frequency should be as close as possible to 1 MHz. This patch
adds warnings when clock is unreliable, according to i.MX datasheet.

Signed-off-by: default avatarAlexander Shiyan <shc_work@mail.ru>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a0822637

drivers/w1/masters/mxc_w1.c

+12 −2
Original line number Diff line number Diff line
@@ -105,6 +105,7 @@ static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit) 
static int mxc_w1_probe(struct platform_device *pdev)

{

	struct mxc_w1_device *mdev;

	unsigned long clkrate;

	struct resource *res;

	unsigned int clkdiv;

	int err = 0;
@@ -118,7 +119,16 @@ static int mxc_w1_probe(struct platform_device *pdev) 
	if (IS_ERR(mdev->clk))

		return PTR_ERR(mdev->clk);



	clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;

	clkrate = clk_get_rate(mdev->clk);

	if (clkrate < 10000000)

		dev_warn(&pdev->dev,

			 "Low clock frequency causes improper function\n");



	clkdiv = DIV_ROUND_CLOSEST(clkrate, 1000000);

	clkrate /= clkdiv;

	if ((clkrate < 980000) || (clkrate > 1020000))

		dev_warn(&pdev->dev,

			 "Incorrect time base frequency %lu Hz\n", clkrate);



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	mdev->regs = devm_ioremap_resource(&pdev->dev, res);
@@ -126,7 +136,7 @@ static int mxc_w1_probe(struct platform_device *pdev) 
		return PTR_ERR(mdev->regs);



	clk_prepare_enable(mdev->clk);

	__raw_writeb(clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);

	__raw_writeb(clkdiv - 1, mdev->regs + MXC_W1_TIME_DIVIDER);



	mdev->bus_master.data = mdev;

	mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus;