From: Fugang Duan Date: Fri, 27 Sep 2013 07:13:19 +0000 (+0800) Subject: ENGR00281611 i2c: imx: update i2c clock divider for each transaction X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=26cca5b0404d2bff637efb6e486fe128be15cd5a;p=karo-tx-linux.git ENGR00281611 i2c: imx: update i2c clock divider for each transaction i.MX6 I2C clk is from IPG_PERCLK which is sourced from IPG_CLK. Under normal operation, IPG_CLK is 66MHz, ipg_perclk is at 22MHz. In low bus freq mode, IPG_CLK is at 12MHz and IPG_PERCLK is down to 4MHz. So the I2C driver must update the divider register for each transaction when the current IPG_PERCLK is not equal to the clock of previous transaction. Signed-off-by: Fugang Duan --- diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 82f20c60bb7b..9782527a8668 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -97,7 +97,7 @@ * Duplicated divider values removed from list */ -static u16 __initdata i2c_clk_div[50][2] = { +static u16 i2c_clk_div[50][2] = { { 22, 0x20 }, { 24, 0x21 }, { 26, 0x22 }, { 28, 0x23 }, { 30, 0x00 }, { 32, 0x24 }, { 36, 0x25 }, { 40, 0x26 }, { 42, 0x03 }, { 44, 0x27 }, { 48, 0x28 }, { 52, 0x05 }, @@ -128,6 +128,9 @@ struct imx_i2c_struct { int stopped; unsigned int ifdr; /* IMX_I2C_IFDR */ enum imx_i2c_type devtype; + + unsigned int cur_clk; + unsigned int bitrate; }; static struct platform_device_id imx_i2c_devtype[] = { @@ -205,6 +208,49 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx) return 0; } +static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx) +{ + unsigned int i2c_clk_rate; + unsigned int div; + int i; + + /* Divider value calculation */ + i2c_clk_rate = clk_get_rate(i2c_imx->clk); + if (i2c_imx->cur_clk == i2c_clk_rate) + return; + else + i2c_imx->cur_clk = i2c_clk_rate; + + div = (i2c_clk_rate + i2c_imx->bitrate - 1) / i2c_imx->bitrate; + if (div < i2c_clk_div[0][0]) + i = 0; + else if (div > i2c_clk_div[ARRAY_SIZE(i2c_clk_div) - 1][0]) + i = ARRAY_SIZE(i2c_clk_div) - 1; + else + for (i = 0; i2c_clk_div[i][0] < div; i++) + ; + + /* Store divider value */ + i2c_imx->ifdr = i2c_clk_div[i][1]; + + /* + * There dummy delay is calculated. + * It should be about one I2C clock period long. + * This delay is used in I2C bus disable function + * to fix chip hardware bug. + */ + i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0] + + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); + + /* dev_dbg() can't be used, because adapter is not yet registered */ +#ifdef CONFIG_I2C_DEBUG_BUS + dev_dbg(&i2c_imx->adapter.dev, "<%s> I2C_CLK=%d, REQ DIV=%d\n", + __func__, i2c_clk_rate, div); + dev_dbg(&i2c_imx->adapter.dev, "<%s> IFDR[IC]=0x%x, REAL DIV=%d\n", + __func__, i2c_clk_div[i][1], i2c_clk_div[i][0]); +#endif +} + static int i2c_imx_start(struct imx_i2c_struct *i2c_imx) { unsigned int temp = 0; @@ -212,6 +258,7 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx) dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); + i2c_imx_set_clk(i2c_imx); clk_prepare_enable(i2c_imx->clk); writeb(i2c_imx->ifdr, i2c_imx->base + IMX_I2C_IFDR); /* Enable I2C controller */ @@ -264,44 +311,6 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx) clk_disable_unprepare(i2c_imx->clk); } -static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx, - unsigned int rate) -{ - unsigned int i2c_clk_rate; - unsigned int div; - int i; - - /* Divider value calculation */ - i2c_clk_rate = clk_get_rate(i2c_imx->clk); - div = (i2c_clk_rate + rate - 1) / rate; - if (div < i2c_clk_div[0][0]) - i = 0; - else if (div > i2c_clk_div[ARRAY_SIZE(i2c_clk_div) - 1][0]) - i = ARRAY_SIZE(i2c_clk_div) - 1; - else - for (i = 0; i2c_clk_div[i][0] < div; i++); - - /* Store divider value */ - i2c_imx->ifdr = i2c_clk_div[i][1]; - - /* - * There dummy delay is calculated. - * It should be about one I2C clock period long. - * This delay is used in I2C bus disable function - * to fix chip hardware bug. - */ - i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0] - + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); - - /* dev_dbg() can't be used, because adapter is not yet registered */ -#ifdef CONFIG_I2C_DEBUG_BUS - dev_dbg(&i2c_imx->adapter.dev, "<%s> I2C_CLK=%d, REQ DIV=%d\n", - __func__, i2c_clk_rate, div); - dev_dbg(&i2c_imx->adapter.dev, "<%s> IFDR[IC]=0x%x, REAL DIV=%d\n", - __func__, i2c_clk_div[i][1], i2c_clk_div[i][0]); -#endif -} - static irqreturn_t i2c_imx_isr(int irq, void *dev_id) { struct imx_i2c_struct *i2c_imx = dev_id; @@ -496,7 +505,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev) struct pinctrl *pinctrl; void __iomem *base; int irq, ret; - u32 bitrate; dev_dbg(&pdev->dev, "<%s>\n", __func__); @@ -563,12 +571,12 @@ static int __init i2c_imx_probe(struct platform_device *pdev) i2c_set_adapdata(&i2c_imx->adapter, i2c_imx); /* Set up clock divider */ - bitrate = IMX_I2C_BIT_RATE; + i2c_imx->bitrate = IMX_I2C_BIT_RATE; ret = of_property_read_u32(pdev->dev.of_node, - "clock-frequency", &bitrate); + "clock-frequency", &i2c_imx->bitrate); if (ret < 0 && pdata && pdata->bitrate) - bitrate = pdata->bitrate; - i2c_imx_set_clk(i2c_imx, bitrate); + i2c_imx->bitrate = pdata->bitrate; + i2c_imx_set_clk(i2c_imx); /* Set up chip registers to defaults */ writeb(0, i2c_imx->base + IMX_I2C_I2CR);