From mboxrd@z Thu Jan 1 00:00:00 1970 From: guy.shapiro@mobi-wize.com (Guy Shapiro) Date: Sun, 27 Nov 2016 09:44:58 +0200 Subject: [PATCH 2/2] input: touchscreen: sample averaging for imx6ul_tsc In-Reply-To: <1480232698-23075-1-git-send-email-guy.shapiro@mobi-wize.com> References: <1480232698-23075-1-git-send-email-guy.shapiro@mobi-wize.com> Message-ID: <1480232698-23075-2-git-send-email-guy.shapiro@mobi-wize.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The i.MX6UL internal touchscreen controller contains an option to average upon samples. This feature reduces noise from the produced touch locations. This patch adds sample averaging support to the imx6ul_tsc device driver. Signed-off-by: Guy Shapiro --- drivers/input/touchscreen/imx6ul_tsc.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/input/touchscreen/imx6ul_tsc.c b/drivers/input/touchscreen/imx6ul_tsc.c index 8275267..31724d9 100644 --- a/drivers/input/touchscreen/imx6ul_tsc.c +++ b/drivers/input/touchscreen/imx6ul_tsc.c @@ -25,6 +25,7 @@ /* ADC configuration registers field define */ #define ADC_AIEN (0x1 << 7) #define ADC_CONV_DISABLE 0x1F +#define ADC_AVGE (0x1 << 5) #define ADC_CAL (0x1 << 7) #define ADC_CALF 0x2 #define ADC_12BIT_MODE (0x2 << 2) @@ -32,6 +33,7 @@ #define ADC_CLK_DIV_8 (0x03 << 5) #define ADC_SHORT_SAMPLE_MODE (0x0 << 4) #define ADC_HARDWARE_TRIGGER (0x1 << 13) +#define ADC_AVGS_SHIFT 14 #define SELECT_CHANNEL_4 0x04 #define SELECT_CHANNEL_1 0x01 #define DISABLE_CONVERSION_INT (0x0 << 7) @@ -86,6 +88,7 @@ struct imx6ul_tsc { int measure_delay_time; int pre_charge_time; + int average_samples; struct completion completion; }; @@ -107,6 +110,8 @@ static int imx6ul_adc_init(struct imx6ul_tsc *tsc) adc_cfg = readl(tsc->adc_regs + REG_ADC_CFG); adc_cfg |= ADC_12BIT_MODE | ADC_IPG_CLK; adc_cfg |= ADC_CLK_DIV_8 | ADC_SHORT_SAMPLE_MODE; + if (tsc->average_samples) + adc_cfg |= (tsc->average_samples - 1) << ADC_AVGS_SHIFT; adc_cfg &= ~ADC_HARDWARE_TRIGGER; writel(adc_cfg, tsc->adc_regs + REG_ADC_CFG); @@ -118,6 +123,8 @@ static int imx6ul_adc_init(struct imx6ul_tsc *tsc) /* start ADC calibration */ adc_gc = readl(tsc->adc_regs + REG_ADC_GC); adc_gc |= ADC_CAL; + if (tsc->average_samples) + adc_gc |= ADC_AVGE; writel(adc_gc, tsc->adc_regs + REG_ADC_GC); timeout = wait_for_completion_timeout @@ -450,6 +457,16 @@ static int imx6ul_tsc_probe(struct platform_device *pdev) if (err) tsc->pre_charge_time = 0xfff; + err = of_property_read_u32(np, "average-samples", + &tsc->average_samples); + if (err) + tsc->average_samples = 0; + if (tsc->average_samples > 4) { + dev_err(&pdev->dev, "average-samples (%u) must be [0-4]\n", + tsc->average_samples); + return -EINVAL; + } + err = input_register_device(tsc->input); if (err) { dev_err(&pdev->dev, -- 2.1.4