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path: root/drivers/iio/adc/ingenic-adc.c
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Diffstat (limited to 'drivers/iio/adc/ingenic-adc.c')
-rw-r--r--drivers/iio/adc/ingenic-adc.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c
index 92b1d5037ac9..e234970b7150 100644
--- a/drivers/iio/adc/ingenic-adc.c
+++ b/drivers/iio/adc/ingenic-adc.c
@@ -11,6 +11,7 @@
#include <linux/iio/iio.h>
#include <linux/io.h>
#include <linux/iopoll.h>
+#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
@@ -22,8 +23,11 @@
#define JZ_ADC_REG_ADTCH 0x18
#define JZ_ADC_REG_ADBDAT 0x1c
#define JZ_ADC_REG_ADSDAT 0x20
+#define JZ_ADC_REG_ADCLK 0x28
#define JZ_ADC_REG_CFG_BAT_MD BIT(4)
+#define JZ_ADC_REG_ADCLK_CLKDIV_LSB 0
+#define JZ_ADC_REG_ADCLK_CLKDIV10US_LSB 16
#define JZ_ADC_AUX_VREF 3300
#define JZ_ADC_AUX_VREF_BITS 12
@@ -34,6 +38,8 @@
#define JZ4740_ADC_BATTERY_HIGH_VREF (7500 * 0.986)
#define JZ4740_ADC_BATTERY_HIGH_VREF_BITS 12
+struct ingenic_adc;
+
struct ingenic_adc_soc_data {
unsigned int battery_high_vref;
unsigned int battery_high_vref_bits;
@@ -41,6 +47,7 @@ struct ingenic_adc_soc_data {
size_t battery_raw_avail_size;
const int *battery_scale_avail;
size_t battery_scale_avail_size;
+ int (*init_clk_div)(struct device *dev, struct ingenic_adc *adc);
};
struct ingenic_adc {
@@ -151,6 +158,42 @@ static const int jz4740_adc_battery_scale_avail[] = {
JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
};
+static int jz4725b_adc_init_clk_div(struct device *dev, struct ingenic_adc *adc)
+{
+ struct clk *parent_clk;
+ unsigned long parent_rate, rate;
+ unsigned int div_main, div_10us;
+
+ parent_clk = clk_get_parent(adc->clk);
+ if (!parent_clk) {
+ dev_err(dev, "ADC clock has no parent\n");
+ return -ENODEV;
+ }
+ parent_rate = clk_get_rate(parent_clk);
+
+ /*
+ * The JZ4725B ADC works at 500 kHz to 8 MHz.
+ * We pick the highest rate possible.
+ * In practice we typically get 6 MHz, half of the 12 MHz EXT clock.
+ */
+ div_main = DIV_ROUND_UP(parent_rate, 8000000);
+ div_main = clamp(div_main, 1u, 64u);
+ rate = parent_rate / div_main;
+ if (rate < 500000 || rate > 8000000) {
+ dev_err(dev, "No valid divider for ADC main clock\n");
+ return -EINVAL;
+ }
+
+ /* We also need a divider that produces a 10us clock. */
+ div_10us = DIV_ROUND_UP(rate, 100000);
+
+ writel(((div_10us - 1) << JZ_ADC_REG_ADCLK_CLKDIV10US_LSB) |
+ (div_main - 1) << JZ_ADC_REG_ADCLK_CLKDIV_LSB,
+ adc->base + JZ_ADC_REG_ADCLK);
+
+ return 0;
+}
+
static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
.battery_high_vref = JZ4725B_ADC_BATTERY_HIGH_VREF,
.battery_high_vref_bits = JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
@@ -158,6 +201,7 @@ static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
.battery_raw_avail_size = ARRAY_SIZE(jz4725b_adc_battery_raw_avail),
.battery_scale_avail = jz4725b_adc_battery_scale_avail,
.battery_scale_avail_size = ARRAY_SIZE(jz4725b_adc_battery_scale_avail),
+ .init_clk_div = jz4725b_adc_init_clk_div,
};
static const struct ingenic_adc_soc_data jz4740_adc_soc_data = {
@@ -167,6 +211,7 @@ static const struct ingenic_adc_soc_data jz4740_adc_soc_data = {
.battery_raw_avail_size = ARRAY_SIZE(jz4740_adc_battery_raw_avail),
.battery_scale_avail = jz4740_adc_battery_scale_avail,
.battery_scale_avail_size = ARRAY_SIZE(jz4740_adc_battery_scale_avail),
+ .init_clk_div = NULL, /* no ADCLK register on JZ4740 */
};
static int ingenic_adc_read_avail(struct iio_dev *iio_dev,
@@ -317,6 +362,15 @@ static int ingenic_adc_probe(struct platform_device *pdev)
return ret;
}
+ /* Set clock dividers. */
+ if (soc_data->init_clk_div) {
+ ret = soc_data->init_clk_div(dev, adc);
+ if (ret) {
+ clk_disable_unprepare(adc->clk);
+ return ret;
+ }
+ }
+
/* Put hardware in a known passive state. */
writeb(0x00, adc->base + JZ_ADC_REG_ENABLE);
writeb(0xff, adc->base + JZ_ADC_REG_CTRL);