diff options
| author | Alexander Shiyan <shc_work@mail.ru> | 2013-11-29 15:39:29 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-08 22:41:48 -0800 |
| commit | 71531f55a83dcb79b89287f6b11fb2e4eb496d4d (patch) | |
| tree | 0bc285ba536bc15dc5d425b0de27e2a0a3607f3b | |
| parent | a0822637258b9e6132de669ac16dfe445c78e932 (diff) | |
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: Alexander Shiyan <shc_work@mail.ru>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/w1/masters/mxc_w1.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/w1/masters/mxc_w1.c b/drivers/w1/masters/mxc_w1.c index 5de3ca9b0fb9..953168c63392 100644 --- a/drivers/w1/masters/mxc_w1.c +++ b/drivers/w1/masters/mxc_w1.c @@ -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; |