From c22d2672c826a67a84fa60c17797315f4c94cedb Mon Sep 17 00:00:00 2001 From: Stefan Wahren Date: Mon, 29 Dec 2014 10:27:21 +0000 Subject: [PATCH] iio: mxs-lradc: check ranges of ts properties The devicetree binding for mxs-lradc defines ranges for the touchscreen properties. In order to avoid unexpected behavior like division by zero, we better check these ranges during probe and abort in error case. Additionally this patch adds an important note from the reference manual about the range of sample delay. Signed-off-by: Stefan Wahren Reviewed-by: Marek Vasut Signed-off-by: Jonathan Cameron --- drivers/staging/iio/adc/mxs-lradc.c | 45 ++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 10 deletions(-) diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c index 6757f107faf3..e0e91836eec1 100644 --- a/drivers/staging/iio/adc/mxs-lradc.c +++ b/drivers/staging/iio/adc/mxs-lradc.c @@ -436,7 +436,14 @@ static void mxs_lradc_setup_ts_channel(struct mxs_lradc *lradc, unsigned ch) */ mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch)); - /* prepare the delay/loop unit according to the oversampling count */ + /* + * prepare the delay/loop unit according to the oversampling count + * + * from the datasheet: + * "The DELAY fields in HW_LRADC_DELAY0, HW_LRADC_DELAY1, + * HW_LRADC_DELAY2, and HW_LRADC_DELAY3 must be non-zero; otherwise, + * the LRADC will not trigger the delay group." + */ mxs_lradc_reg_wrt(lradc, LRADC_DELAY_TRIGGER(1 << ch) | LRADC_DELAY_TRIGGER_DELAYS(0) | LRADC_DELAY_LOOP(lradc->over_sample_cnt - 1) | @@ -1495,20 +1502,38 @@ static int mxs_lradc_probe_touchscreen(struct mxs_lradc *lradc, return -EINVAL; } - lradc->over_sample_cnt = 4; - ret = of_property_read_u32(lradc_node, "fsl,ave-ctrl", &adapt); - if (ret == 0) + if (of_property_read_u32(lradc_node, "fsl,ave-ctrl", &adapt)) { + lradc->over_sample_cnt = 4; + } else { + if (adapt < 1 || adapt > 32) { + dev_err(lradc->dev, "Invalid sample count (%u)\n", + adapt); + return -EINVAL; + } lradc->over_sample_cnt = adapt; + } - lradc->over_sample_delay = 2; - ret = of_property_read_u32(lradc_node, "fsl,ave-delay", &adapt); - if (ret == 0) + if (of_property_read_u32(lradc_node, "fsl,ave-delay", &adapt)) { + lradc->over_sample_delay = 2; + } else { + if (adapt < 2 || adapt > LRADC_DELAY_DELAY_MASK + 1) { + dev_err(lradc->dev, "Invalid sample delay (%u)\n", + adapt); + return -EINVAL; + } lradc->over_sample_delay = adapt; + } - lradc->settling_delay = 10; - ret = of_property_read_u32(lradc_node, "fsl,settling", &adapt); - if (ret == 0) + if (of_property_read_u32(lradc_node, "fsl,settling", &adapt)) { + lradc->settling_delay = 10; + } else { + if (adapt < 1 || adapt > LRADC_DELAY_DELAY_MASK) { + dev_err(lradc->dev, "Invalid settling delay (%u)\n", + adapt); + return -EINVAL; + } lradc->settling_delay = adapt; + } return 0; } -- 2.30.2