On stm32h7 and stm32mp1, the ADC inputs are multiplexed with analog
switches which have reduced performances when their supply is below 2.7V
(vdda by default):
- 3.3V embedded booster can be used, to get full ADC performances
(increases power consumption).
- vdd supply can be selected if above 2.7V by setting ANASWVDD syscfg bit,
on STM32MP1 only.
Make this optional, since this is a trade-off between analog performance
and power consumption.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
---
Changes in v2:
- Only enable vdd regulator when needed.
- Rework vdda enabling since: "Add missing vdda-supply to STM32 ADC".
- Booster has been added to the regulator framework. This helps also when
there are several ADC instances like on stm32h7 (e.g. ADC12 and ADC3), to
benefit from the use count.
---
drivers/iio/adc/stm32-adc-core.c | 193 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 192 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c
index 1f7ce51..4299cef 100644
--- a/drivers/iio/adc/stm32-adc-core.c
+++ b/drivers/iio/adc/stm32-adc-core.c
@@ -14,9 +14,11 @@
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdesc.h>
#include <linux/irqdomain.h>
+#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
@@ -51,6 +53,17 @@
#define STM32_ADC_CORE_SLEEP_DELAY_MS 2000
+/* SYSCFG registers */
+#define STM32MP1_SYSCFG_PMCSETR 0x04
+#define STM32MP1_SYSCFG_PMCCLRR 0x44
+
+/* SYSCFG bit fields */
+#define STM32MP1_SYSCFG_ANASWVDD_MASK BIT(9)
+
+/* SYSCFG capability flags */
+#define HAS_VBOOSTER BIT(0)
+#define HAS_ANASWVDD BIT(1)
+
/**
* stm32_adc_common_regs - stm32 common registers, compatible dependent data
* @csr: common status register offset
@@ -74,11 +87,13 @@ struct stm32_adc_priv;
* @regs: common registers for all instances
* @clk_sel: clock selection routine
* @max_clk_rate_hz: maximum analog clock rate (Hz, from datasheet)
+ * @has_syscfg: SYSCFG capability flags
*/
struct stm32_adc_priv_cfg {
const struct stm32_adc_common_regs *regs;
int (*clk_sel)(struct platform_device *, struct stm32_adc_priv *);
u32 max_clk_rate_hz;
+ unsigned int has_syscfg;
};
/**
@@ -87,22 +102,32 @@ 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
+ * @booster: booster supply reference
+ * @vdd: vdd supply reference
* @vdda: vdda analog supply reference
* @vref: regulator reference
+ * @vdd_uv: vdd supply voltage (microvolts)
+ * @vdda_uv: vdda supply voltage (microvolts)
* @cfg: compatible configuration data
* @common: common data for all ADC instances
* @ccr_bak: backup CCR in low power mode
+ * @syscfg: reference to syscon, system control registers
*/
struct stm32_adc_priv {
int irq[STM32_ADC_MAX_ADCS];
struct irq_domain *domain;
struct clk *aclk;
struct clk *bclk;
+ struct regulator *booster;
+ struct regulator *vdd;
struct regulator *vdda;
struct regulator *vref;
+ int vdd_uv;
+ int vdda_uv;
const struct stm32_adc_priv_cfg *cfg;
struct stm32_adc_common common;
u32 ccr_bak;
+ struct regmap *syscfg;
};
static struct stm32_adc_priv *to_stm32_adc_priv(struct stm32_adc_common *com)
@@ -390,6 +415,82 @@ static void stm32_adc_irq_remove(struct platform_device *pdev,
}
}
+static int stm32_adc_core_switches_supply_en(struct stm32_adc_priv *priv,
+ struct device *dev)
+{
+ int ret;
+
+ /*
+ * On STM32H7 and STM32MP1, the ADC inputs are multiplexed with analog
+ * switches (via PCSEL) which have reduced performances when their
+ * supply is below 2.7V (vdda by default):
+ * - Voltage booster can be used, to get full ADC performances
+ * (increases power consumption).
+ * - Vdd can be used to supply them, if above 2.7V (STM32MP1 only).
+ *
+ * Recommended settings for ANASWVDD and EN_BOOSTER:
+ * - vdda < 2.7V but vdd > 2.7V: ANASWVDD = 1, EN_BOOSTER = 0 (stm32mp1)
+ * - vdda < 2.7V and vdd < 2.7V: ANASWVDD = 0, EN_BOOSTER = 1
+ * - vdda >= 2.7V: ANASWVDD = 0, EN_BOOSTER = 0 (default)
+ */
+ if (priv->vdda_uv < 2700000) {
+ if (priv->syscfg && priv->vdd_uv > 2700000) {
+ ret = regulator_enable(priv->vdd);
+ if (ret < 0) {
+ dev_err(dev, "vdd enable failed %d\n", ret);
+ return ret;
+ }
+
+ ret = regmap_write(priv->syscfg,
+ STM32MP1_SYSCFG_PMCSETR,
+ STM32MP1_SYSCFG_ANASWVDD_MASK);
+ if (ret < 0) {
+ regulator_disable(priv->vdd);
+ dev_err(dev, "vdd select failed, %d\n", ret);
+ return ret;
+ }
+ dev_dbg(dev, "analog switches supplied by vdd\n");
+
+ return 0;
+ }
+
+ if (priv->booster) {
+ /*
+ * This is optional, as this is a trade-off between
+ * analog performance and power consumption.
+ */
+ ret = regulator_enable(priv->booster);
+ if (ret < 0) {
+ dev_err(dev, "booster enable failed %d\n", ret);
+ return ret;
+ }
+ dev_dbg(dev, "analog switches supplied by booster\n");
+
+ return 0;
+ }
+ }
+
+ /* Fallback using vdda (default), nothing to do */
+ dev_dbg(dev, "analog switches supplied by vdda (%d uV)\n",
+ priv->vdda_uv);
+
+ return 0;
+}
+
+static void stm32_adc_core_switches_supply_dis(struct stm32_adc_priv *priv)
+{
+ if (priv->vdda_uv < 2700000) {
+ if (priv->syscfg && priv->vdd_uv > 2700000) {
+ regmap_write(priv->syscfg, STM32MP1_SYSCFG_PMCCLRR,
+ STM32MP1_SYSCFG_ANASWVDD_MASK);
+ regulator_disable(priv->vdd);
+ return;
+ }
+ if (priv->booster)
+ regulator_disable(priv->booster);
+ }
+}
+
static int stm32_adc_core_hw_start(struct device *dev)
{
struct stm32_adc_common *common = dev_get_drvdata(dev);
@@ -402,10 +503,21 @@ static int stm32_adc_core_hw_start(struct device *dev)
return ret;
}
+ ret = regulator_get_voltage(priv->vdda);
+ if (ret < 0) {
+ dev_err(dev, "vdda get voltage failed, %d\n", ret);
+ goto err_vdda_disable;
+ }
+ priv->vdda_uv = ret;
+
+ ret = stm32_adc_core_switches_supply_en(priv, dev);
+ if (ret < 0)
+ goto err_vdda_disable;
+
ret = regulator_enable(priv->vref);
if (ret < 0) {
dev_err(dev, "vref enable failed\n");
- goto err_vdda_disable;
+ goto err_switches_dis;
}
if (priv->bclk) {
@@ -433,6 +545,8 @@ static int stm32_adc_core_hw_start(struct device *dev)
clk_disable_unprepare(priv->bclk);
err_regulator_disable:
regulator_disable(priv->vref);
+err_switches_dis:
+ stm32_adc_core_switches_supply_dis(priv);
err_vdda_disable:
regulator_disable(priv->vdda);
@@ -451,9 +565,80 @@ static void stm32_adc_core_hw_stop(struct device *dev)
if (priv->bclk)
clk_disable_unprepare(priv->bclk);
regulator_disable(priv->vref);
+ stm32_adc_core_switches_supply_dis(priv);
regulator_disable(priv->vdda);
}
+static int stm32_adc_core_switches_probe(struct device *dev,
+ struct stm32_adc_priv *priv)
+{
+ struct device_node *np = dev->of_node;
+ int ret;
+
+ /* Analog switches supply can be controlled by syscfg (optional) */
+ priv->syscfg = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
+ if (IS_ERR(priv->syscfg)) {
+ ret = PTR_ERR(priv->syscfg);
+ if (ret != -ENODEV) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "Can't probe syscfg: %d\n", ret);
+ return ret;
+ }
+ priv->syscfg = NULL;
+ }
+
+ /* Booster can be used to supply analog switches (optional) */
+ if (priv->cfg->has_syscfg & HAS_VBOOSTER &&
+ of_property_read_bool(np, "booster-supply")) {
+ priv->booster = devm_regulator_get_optional(dev, "booster");
+ if (IS_ERR(priv->booster)) {
+ ret = PTR_ERR(priv->booster);
+ if (ret != -ENODEV) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "can't get booster %d\n",
+ ret);
+ return ret;
+ }
+ priv->booster = NULL;
+ }
+ }
+
+ /* Vdd can be used to supply analog switches (optional) */
+ if (priv->cfg->has_syscfg & HAS_ANASWVDD &&
+ of_property_read_bool(np, "vdd-supply")) {
+ priv->vdd = devm_regulator_get_optional(dev, "vdd");
+ if (IS_ERR(priv->vdd)) {
+ ret = PTR_ERR(priv->vdd);
+ if (ret != -ENODEV) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "can't get vdd %d\n", ret);
+ return ret;
+ }
+ priv->vdd = NULL;
+ }
+ }
+
+ if (priv->vdd) {
+ ret = regulator_enable(priv->vdd);
+ if (ret < 0) {
+ dev_err(dev, "vdd enable failed %d\n", ret);
+ return ret;
+ }
+
+ ret = regulator_get_voltage(priv->vdd);
+ if (ret < 0) {
+ dev_err(dev, "vdd get voltage failed %d\n", ret);
+ regulator_disable(priv->vdd);
+ return ret;
+ }
+ priv->vdd_uv = ret;
+
+ regulator_disable(priv->vdd);
+ }
+
+ return 0;
+}
+
static int stm32_adc_probe(struct platform_device *pdev)
{
struct stm32_adc_priv *priv;
@@ -514,6 +699,10 @@ static int stm32_adc_probe(struct platform_device *pdev)
priv->bclk = NULL;
}
+ ret = stm32_adc_core_switches_probe(dev, priv);
+ if (ret)
+ return ret;
+
pm_runtime_get_noresume(dev);
pm_runtime_set_active(dev);
pm_runtime_set_autosuspend_delay(dev, STM32_ADC_CORE_SLEEP_DELAY_MS);
@@ -611,12 +800,14 @@ static const struct stm32_adc_priv_cfg stm32h7_adc_priv_cfg = {
.regs = &stm32h7_adc_common_regs,
.clk_sel = stm32h7_adc_clk_sel,
.max_clk_rate_hz = 36000000,
+ .has_syscfg = HAS_VBOOSTER,
};
static const struct stm32_adc_priv_cfg stm32mp1_adc_priv_cfg = {
.regs = &stm32h7_adc_common_regs,
.clk_sel = stm32h7_adc_clk_sel,
.max_clk_rate_hz = 40000000,
+ .has_syscfg = HAS_VBOOSTER | HAS_ANASWVDD,
};
static const struct of_device_id stm32_adc_of_match[] = {
--
2.7.4
