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thermal/drivers/airoha: Serialise access to the shared ADC

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A read selects the sensor and walks three diodes with a 10 ms settle on
each. The zone lock serialises reads of one zone. With a zone per AN7583
sensor, added later in this series, reads of different zones interleave
and convert samples taken at another mux position.

Mux writes are dropped silently unless PLLRG_PROTECT is lifted, and its
save and restore do not nest. The cached TADC value also skips a write
after another reader has moved the mux.

With the AN7583 sensors read as parallel zones during CPU frequency
changes, a zone crossed its critical trip on a chip at 55 C and the
board shut down.

Serialise the sequence, drop the cache, check the selection after
writing and after sampling, and return -EAGAIN if it does not hold.

Signed-off-by: Vitaliy Sochnev <sochnev.v.74@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>
Link: https://patch.msgid.link/20260929165209.69669-3-sochnev.v.74@gmail.com
This commit is contained in:
Vitaliy Sochnev 2026-09-29 19:52:07 +03:00 committed by Daniel Lezcano
parent 4a0f3193c6
commit b1bf55053a
1 changed files with 68 additions and 17 deletions
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85
drivers/thermal/airoha_thermal.c
View File

@ -5,6 +5,7 @@
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/mfd/syscon.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
@ -191,6 +192,7 @@
#define AN7583_NUM_SENSOR 3
#define AIROHA_THERMAL_NO_MUX_SENSOR -1
#define AIROHA_THERMAL_MUX_TRIES 3
/* Convert temp to raw value as read from ADC ((((temp / 100) - init) * slope) / 1000) + offset */
#define TEMP_TO_RAW(priv, temp) ((((((temp) / 100) - (priv)->init_temp) * \
@ -250,7 +252,8 @@ struct airoha_thermal_priv {
struct resource scu_adc_res;
u32 pllrg_protect;
int current_adc;
/* Serialises mux selection and ADC sampling */
struct mutex lock;
struct thermal_zone_device *tz;
int init_temp;
@ -294,9 +297,26 @@ static int airoha_get_thermal_ADC(struct airoha_thermal_priv *priv)
return val;
}
static bool airoha_thermal_mux_holds(struct airoha_thermal_priv *priv,
int tdac_idx, int sensor_idx)
{
unsigned int val;
if (regmap_field_read(priv->chip_scu_fields[AIROHA_THERMAL_MUX_TADC], &val) ||
val != tdac_idx)
return false;
if (sensor_idx == AIROHA_THERMAL_NO_MUX_SENSOR)
return true;
return !regmap_field_read(priv->chip_scu_fields[AIROHA_THERMAL_MUX_SENSOR], &val) &&
val == sensor_idx;
}
static void airoha_set_thermal_mux(struct airoha_thermal_priv *priv,
int tdac_idx, int sensor_idx)
{
int tries = AIROHA_THERMAL_MUX_TRIES;
u32 pllrg;
/* Save PLLRG current value */
@ -307,19 +327,17 @@ static void airoha_set_thermal_mux(struct airoha_thermal_priv *priv,
priv->pllrg_protect);
/*
* Configure Thermal Sensor mux to sensor_idx.
* Configure Thermal Sensor mux to sensor_idx and Thermal ADC mux to
* tdac_idx. Writes can be dropped silently, so read them back.
* (if not supported, sensor_idx is AIROHA_THERMAL_NO_MUX_SENSOR)
*/
if (sensor_idx != AIROHA_THERMAL_NO_MUX_SENSOR)
regmap_field_write(priv->chip_scu_fields[AIROHA_THERMAL_MUX_SENSOR],
sensor_idx);
/* Configure Thermal ADC mux to tdac_idx */
if (priv->current_adc != tdac_idx) {
do {
if (sensor_idx != AIROHA_THERMAL_NO_MUX_SENSOR)
regmap_field_write(priv->chip_scu_fields[AIROHA_THERMAL_MUX_SENSOR],
sensor_idx);
regmap_field_write(priv->chip_scu_fields[AIROHA_THERMAL_MUX_TADC],
tdac_idx);
priv->current_adc = tdac_idx;
}
} while (!airoha_thermal_mux_holds(priv, tdac_idx, sensor_idx) && --tries);
/* Restore PLLRG value on exit */
regmap_write(priv->chip_scu, EN7581_PLLRG_PROTECT, pllrg);
@ -596,12 +614,40 @@ static int en7581_thermal_post_probe(struct platform_device *pdev)
return 0;
}
static int an7583_thermal_read_diode(struct airoha_thermal_priv *priv,
int diode, int sensor_idx, int *val)
{
airoha_set_thermal_mux(priv, diode, sensor_idx);
*val = airoha_get_thermal_ADC(priv);
return airoha_thermal_mux_holds(priv, diode, sensor_idx) ? 0 : -EAGAIN;
}
static int an7583_thermal_read_diodes(struct airoha_thermal_priv *priv,
int sensor_idx, int *zero, int *d0,
int *d1)
{
int ret;
ret = an7583_thermal_read_diode(priv, AN7583_ZERO_TADC, sensor_idx, zero);
if (ret)
return ret;
ret = an7583_thermal_read_diode(priv, AN7583_D0_TADC, sensor_idx, d0);
if (ret)
return ret;
return an7583_thermal_read_diode(priv, AN7583_D1_TADC, sensor_idx, d1);
}
static int an7583_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
{
struct airoha_thermal_priv *priv = thermal_zone_device_priv(tz);
int sensor_idx;
int delta_diode, delta_gain;
int coeff, slope, offset;
int tries = AIROHA_THERMAL_MUX_TRIES;
int ret;
int diode_zero, diode_d0, diode_d1;
@ -612,12 +658,14 @@ static int an7583_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
slope = an7583_thermal_slope[sensor_idx];
offset = an7583_thermal_offset[sensor_idx];
airoha_set_thermal_mux(priv, AN7583_ZERO_TADC, sensor_idx);
diode_zero = airoha_get_thermal_ADC(priv);
airoha_set_thermal_mux(priv, AN7583_D0_TADC, sensor_idx);
diode_d0 = airoha_get_thermal_ADC(priv);
airoha_set_thermal_mux(priv, AN7583_D1_TADC, sensor_idx);
diode_d1 = airoha_get_thermal_ADC(priv);
mutex_lock(&priv->lock);
do {
ret = an7583_thermal_read_diodes(priv, sensor_idx, &diode_zero,
&diode_d0, &diode_d1);
} while (ret == -EAGAIN && --tries);
mutex_unlock(&priv->lock);
if (ret)
return ret;
delta_diode = diode_d1 - diode_d0;
delta_gain = (delta_diode * coeff) / 100 + (diode_zero - diode_d1);
@ -678,7 +726,10 @@ static int airoha_thermal_probe(struct platform_device *pdev)
return -ENOMEM;
priv->pllrg_protect = soc_data->pllrg_protect;
priv->current_adc = -1;
ret = devm_mutex_init(dev, &priv->lock);
if (ret)
return ret;
if (!soc_data->probe)
return -EINVAL;