lkml.org 
[lkml]   [2019]   [Oct]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 2/2] iio: adc: stm32: allow to tune analog clock
Date
Add new optional dt property to tune analog clock prescaler.
Driver looks for optional "st,max-clk-rate-hz", then computes
best approximation below that rate, using ADC internal prescaler.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
drivers/iio/adc/stm32-adc-core.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c
index 20c626c..6537f4f 100644
--- a/drivers/iio/adc/stm32-adc-core.c
+++ b/drivers/iio/adc/stm32-adc-core.c
@@ -79,6 +79,7 @@ struct stm32_adc_priv_cfg {
* @domain: irq domain reference
* @aclk: clock reference for the analog circuitry
* @bclk: bus clock common for all ADCs, depends on part used
+ * @max_clk_rate: desired maximum clock rate
* @booster: booster supply reference
* @vdd: vdd supply reference
* @vdda: vdda analog supply reference
@@ -95,6 +96,7 @@ struct stm32_adc_priv {
struct irq_domain *domain;
struct clk *aclk;
struct clk *bclk;
+ u32 max_clk_rate;
struct regulator *booster;
struct regulator *vdd;
struct regulator *vdda;
@@ -141,7 +143,7 @@ static int stm32f4_adc_clk_sel(struct platform_device *pdev,
}

for (i = 0; i < ARRAY_SIZE(stm32f4_pclk_div); i++) {
- if ((rate / stm32f4_pclk_div[i]) <= priv->cfg->max_clk_rate_hz)
+ if ((rate / stm32f4_pclk_div[i]) <= priv->max_clk_rate)
break;
}
if (i >= ARRAY_SIZE(stm32f4_pclk_div)) {
@@ -230,7 +232,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev,
if (ckmode)
continue;

- if ((rate / div) <= priv->cfg->max_clk_rate_hz)
+ if ((rate / div) <= priv->max_clk_rate)
goto out;
}
}
@@ -250,7 +252,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev,
if (!ckmode)
continue;

- if ((rate / div) <= priv->cfg->max_clk_rate_hz)
+ if ((rate / div) <= priv->max_clk_rate)
goto out;
}

@@ -655,6 +657,7 @@ static int stm32_adc_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct device_node *np = pdev->dev.of_node;
struct resource *res;
+ u32 max_rate;
int ret;

if (!pdev->dev.of_node)
@@ -731,6 +734,13 @@ static int stm32_adc_probe(struct platform_device *pdev)
priv->common.vref_mv = ret / 1000;
dev_dbg(&pdev->dev, "vref+=%dmV\n", priv->common.vref_mv);

+ ret = of_property_read_u32(pdev->dev.of_node, "st,max-clk-rate-hz",
+ &max_rate);
+ if (!ret)
+ priv->max_clk_rate = min(max_rate, priv->cfg->max_clk_rate_hz);
+ else
+ priv->max_clk_rate = priv->cfg->max_clk_rate_hz;
+
ret = priv->cfg->clk_sel(pdev, priv);
if (ret < 0)
goto err_hw_stop;
--
2.7.4
\
 
 \ /
  Last update: 2019-10-28 17:13    [W:0.080 / U:0.604 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site