From 0615adf07d2c0bb5e146e17a2f362946eccc70e5 Mon Sep 17 00:00:00 2001 From: AngeloGioacchino Del Regno Date: Wed, 13 Jan 2021 19:22:24 +0100 Subject: [PATCH] i2c: qup: Introduce SCL/SDA noise rejection Some I2C devices may be glitchy due to electrical noise coming from the device itself or because of possible board design issues. To overcome this issue, the QUP's I2C in Qualcomm SoCs supports a noise rejection setting for both SCL and SDA lines. Introduce a setting for noise rejection through device properties, "qcom,noise-reject-sda" and "qcom,noise-reject-scl", which will be used to set the level of noise rejection sensitivity. If the properties are not specified, noise rejection will not be enabled. Signed-off-by: AngeloGioacchino Del Regno --- drivers/i2c/busses/i2c-qup.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c index 2e153f2f71b6..4b55f0b64e10 100644 --- a/drivers/i2c/busses/i2c-qup.c +++ b/drivers/i2c/busses/i2c-qup.c @@ -39,6 +39,8 @@ #define QUP_MX_READ_CNT 0x208 #define QUP_IN_FIFO_BASE 0x218 #define QUP_I2C_CLK_CTL 0x400 +#define QUP_I2C_CLK_CTL_SDA_NR GENMASK(27, 26) +#define QUP_I2C_CLK_CTL_SCL_NR GENMASK(25, 24) #define QUP_I2C_STATUS 0x404 #define QUP_I2C_MASTER_GEN 0x408 @@ -1663,6 +1665,7 @@ static int qup_i2c_probe(struct platform_device *pdev) int ret, fs_div, hs_div; u32 src_clk_freq = DEFAULT_SRC_CLK; u32 clk_freq = DEFAULT_CLK_FREQ; + u32 noise_reject_scl = 0, noise_reject_sda = 0; int blocks; bool is_qup_v1; @@ -1860,6 +1863,19 @@ nodma: qup->clk_ctl = ((fs_div / 2) << 16) | (hs_div << 8) | (fs_div & 0xff); } + /* SCL/SDA Noise rejection (optional) */ + ret = device_property_read_u32(qup->dev, "qcom,noise-reject-scl", + &noise_reject_scl); + if (ret == 0) + qup->clk_ctl |= FIELD_PREP(QUP_I2C_CLK_CTL_SCL_NR, + noise_reject_scl); + + ret = device_property_read_u32(qup->dev, "qcom,noise-reject-sda", + &noise_reject_sda); + if (ret == 0) + qup->clk_ctl |= FIELD_PREP(QUP_I2C_CLK_CTL_SDA_NR, + noise_reject_sda); + /* * Time it takes for a byte to be clocked out on the bus. * Each byte takes 9 clock cycles (8 bits + 1 ack).