[PATCH 1/3] iio: adc: stm32: fix common clock rate

Fabrice Gasnier
2017-07-18T12:37:22Z

Fixes commit 95e339b6e85d ("iio: adc: stm32: add support for STM32H7")

Fix common clock rate used then by stm32-adc sub-devices: take common
prescaler into account.
Fix ADC max clock rate on STM32H7 (fADC from datasheet)

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
drivers/iio/adc/stm32-adc-core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c
index e09233b..6096763 100644
--- a/drivers/iio/adc/stm32-adc-core.c
+++ b/drivers/iio/adc/stm32-adc-core.c
@@ -64,7 +64,7 @@
#define STM32H7_CKMODE_MASK GENMASK(17, 16)

/* STM32 H7 maximum analog clock rate (from datasheet) */
-#define STM32H7_ADC_MAX_CLK_RATE 72000000
+#define STM32H7_ADC_MAX_CLK_RATE 36000000

/**
* stm32_adc_common_regs - stm32 common registers, compatible dependent data
@@ -148,14 +148,14 @@ static int stm32f4_adc_clk_sel(struct platform_device *pdev,
return -EINVAL;
}

- priv->common.rate = rate;
+ priv->common.rate = rate / stm32f4_pclk_div[i];
val = readl_relaxed(priv->common.base + STM32F4_ADC_CCR);
val &= ~STM32F4_ADC_ADCPRE_MASK;
val |= i << STM32F4_ADC_ADCPRE_SHIFT;
writel_relaxed(val, priv->common.base + STM32F4_ADC_CCR);

dev_dbg(&pdev->dev, "Using analog clock source at %ld kHz\n",
- rate / (stm32f4_pclk_div[i] * 1000));
+ priv->common.rate / 1000);

return 0;
}
@@ -250,7 +250,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev,

out:
/* rate used later by each ADC instance to control BOOST mode */
- priv->common.rate = rate;
+ priv->common.rate = rate / div;

/* Set common clock mode and prescaler */
val = readl_relaxed(priv->common.base + STM32H7_ADC_CCR);
@@ -260,7 +260,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev,
writel_relaxed(val, priv->common.base + STM32H7_ADC_CCR);

dev_dbg(&pdev->dev, "Using %s clock/%d source at %ld kHz\n",
- ckmode ? "bus" : "adc", div, rate / (div * 1000));
+ ckmode ? "bus" : "adc", div, priv->common.rate / 1000);

return 0;
}
--
1.9.1