[PATCH v3 2/3] hwmon: ltc2992: Add support for GPIOs.

From: alexandru.tachici
Date: Thu Dec 03 2020 - 02:08:18 EST

From: Alexandru Tachici <alexandru.tachici@xxxxxxxxxx>

LTC2992 has 4 open-drain GPIOS. This patch exports to user
space the 4 GPIOs using the GPIO driver Linux API.

Signed-off-by: Alexandru Tachici <alexandru.tachici@xxxxxxxxxx>
---
drivers/hwmon/Kconfig | 1 +
drivers/hwmon/ltc2992.c | 160 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 160 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index bf9e387270d6..8a8eb42fb1ec 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -861,6 +861,7 @@ config SENSORS_LTC2990
config SENSORS_LTC2992
tristate "Linear Technology LTC2992"
depends on I2C
+ depends on GPIOLIB
help
If you say yes here you get support for Linear Technology LTC2992
I2C System Monitor. The LTC2992 measures current, voltage, and
diff --git a/drivers/hwmon/ltc2992.c b/drivers/hwmon/ltc2992.c
index c11d585a9600..69dbb5aa5dc2 100644
--- a/drivers/hwmon/ltc2992.c
+++ b/drivers/hwmon/ltc2992.c
@@ -8,6 +8,7 @@
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/err.h>
+#include <linux/gpio/driver.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
@@ -54,6 +55,9 @@
#define LTC2992_G4_MAX_THRESH 0x74
#define LTC2992_G4_MIN_THRESH 0x76
#define LTC2992_FAULT3 0x92
+#define LTC2992_GPIO_STATUS 0x95
+#define LTC2992_GPIO_IO_CTRL 0x96
+#define LTC2992_GPIO_CTRL 0x97

#define LTC2992_POWER(x) (LTC2992_POWER1 + ((x) * 0x32))
#define LTC2992_POWER_MAX(x) (LTC2992_POWER1_MAX + ((x) * 0x32))
@@ -96,8 +100,18 @@
#define LTC2992_VADC_UV_LSB 25000
#define LTC2992_VADC_GPIO_UV_LSB 500

+#define LTC2992_GPIO_NR 4
+#define LTC2992_GPIO1_BIT 7
+#define LTC2992_GPIO2_BIT 6
+#define LTC2992_GPIO3_BIT 0
+#define LTC2992_GPIO4_BIT 6
+#define LTC2992_GPIO_BIT(x) (LTC2992_GPIO_NR - (x) - 1)
+
struct ltc2992_state {
struct i2c_client *client;
+ struct gpio_chip gc;
+ struct mutex gpio_mutex; /* lock for gpio access */
+ const char *gpio_names[LTC2992_GPIO_NR];
struct regmap *regmap;
u32 r_sense_uohm[2];
};
@@ -111,6 +125,8 @@ struct ltc2992_gpio_regs {
u8 alarm;
u8 min_alarm_msk;
u8 max_alarm_msk;
+ u8 ctrl;
+ u8 ctrl_bit;
};

static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
@@ -123,6 +139,8 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
.alarm = LTC2992_FAULT1,
.min_alarm_msk = LTC2992_GPIO1_FAULT_MSK(0),
.max_alarm_msk = LTC2992_GPIO1_FAULT_MSK(1),
+ .ctrl = LTC2992_GPIO_IO_CTRL,
+ .ctrl_bit = LTC2992_GPIO1_BIT,
},
{
.data = LTC2992_G2,
@@ -133,6 +151,8 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
.alarm = LTC2992_FAULT2,
.min_alarm_msk = LTC2992_GPIO2_FAULT_MSK(0),
.max_alarm_msk = LTC2992_GPIO2_FAULT_MSK(1),
+ .ctrl = LTC2992_GPIO_IO_CTRL,
+ .ctrl_bit = LTC2992_GPIO2_BIT,
},
{
.data = LTC2992_G3,
@@ -143,6 +163,8 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
.alarm = LTC2992_FAULT3,
.min_alarm_msk = LTC2992_GPIO3_FAULT_MSK(0),
.max_alarm_msk = LTC2992_GPIO3_FAULT_MSK(1),
+ .ctrl = LTC2992_GPIO_IO_CTRL,
+ .ctrl_bit = LTC2992_GPIO3_BIT,
},
{
.data = LTC2992_G4,
@@ -153,14 +175,20 @@ static const struct ltc2992_gpio_regs ltc2992_gpio_addr_map[] = {
.alarm = LTC2992_FAULT3,
.min_alarm_msk = LTC2992_GPIO4_FAULT_MSK(0),
.max_alarm_msk = LTC2992_GPIO4_FAULT_MSK(1),
+ .ctrl = LTC2992_GPIO_CTRL,
+ .ctrl_bit = LTC2992_GPIO4_BIT,
},
};

+static const char *ltc2992_gpio_names[LTC2992_GPIO_NR] = {
+ "GPIO1", "GPIO2", "GPIO3", "GPIO4",
+};
+
static int ltc2992_read_reg(struct ltc2992_state *st, u8 addr, const u8 reg_len)
{
u8 regvals[4];
- int ret;
int val;
+ int ret;
int i;

ret = regmap_bulk_read(st->regmap, addr, regvals, reg_len);
@@ -185,6 +213,132 @@ static int ltc2992_write_reg(struct ltc2992_state *st, u8 addr, const u8 reg_len
return regmap_bulk_write(st->regmap, addr, regvals, reg_len);
}

+static int ltc2992_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ struct ltc2992_state *st = gpiochip_get_data(chip);
+ unsigned long gpio_status;
+ int reg;
+
+ mutex_lock(&st->gpio_mutex);
+ reg = ltc2992_read_reg(st, LTC2992_GPIO_STATUS, 1);
+ mutex_unlock(&st->gpio_mutex);
+
+ if (reg < 0)
+ return reg;
+
+ gpio_status = reg;
+
+ return !test_bit(LTC2992_GPIO_BIT(offset), &gpio_status);
+}
+
+static int ltc2992_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
+ unsigned long *bits)
+{
+ struct ltc2992_state *st = gpiochip_get_data(chip);
+ unsigned long gpio_status;
+ unsigned int gpio_nr;
+ int reg;
+
+ mutex_lock(&st->gpio_mutex);
+ reg = ltc2992_read_reg(st, LTC2992_GPIO_STATUS, 1);
+ mutex_unlock(&st->gpio_mutex);
+
+ if (reg < 0)
+ return reg;
+
+ gpio_status = reg;
+
+ gpio_nr = 0;
+ for_each_set_bit_from(gpio_nr, mask, LTC2992_GPIO_NR) {
+ if (test_bit(LTC2992_GPIO_BIT(gpio_nr), &gpio_status))
+ set_bit(gpio_nr, bits);
+ }
+
+ return 0;
+}
+
+static void ltc2992_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
+{
+ struct ltc2992_state *st = gpiochip_get_data(chip);
+ unsigned long gpio_ctrl;
+ int reg;
+
+ mutex_lock(&st->gpio_mutex);
+ reg = ltc2992_read_reg(st, ltc2992_gpio_addr_map[offset].ctrl, 1);
+ if (reg < 0) {
+ mutex_unlock(&st->gpio_mutex);
+ return;
+ }
+
+ gpio_ctrl = reg;
+ assign_bit(ltc2992_gpio_addr_map[offset].ctrl_bit, &gpio_ctrl, value);
+
+ ltc2992_write_reg(st, ltc2992_gpio_addr_map[offset].ctrl, 1, gpio_ctrl);
+ mutex_unlock(&st->gpio_mutex);
+}
+
+static void ltc2992_gpio_set_multiple(struct gpio_chip *chip, unsigned long *mask,
+ unsigned long *bits)
+{
+ struct ltc2992_state *st = gpiochip_get_data(chip);
+ unsigned long gpio_ctrl_io = 0;
+ unsigned long gpio_ctrl = 0;
+ unsigned int gpio_nr;
+
+ for_each_set_bit(gpio_nr, mask, LTC2992_GPIO_NR) {
+ if (gpio_nr < 3)
+ assign_bit(ltc2992_gpio_addr_map[gpio_nr].ctrl_bit, &gpio_ctrl_io, true);
+
+ if (gpio_nr == 3)
+ assign_bit(ltc2992_gpio_addr_map[gpio_nr].ctrl_bit, &gpio_ctrl, true);
+ }
+
+ mutex_lock(&st->gpio_mutex);
+ ltc2992_write_reg(st, LTC2992_GPIO_IO_CTRL, 1, gpio_ctrl_io);
+ ltc2992_write_reg(st, LTC2992_GPIO_CTRL, 1, gpio_ctrl);
+ mutex_unlock(&st->gpio_mutex);
+}
+
+static int ltc2992_config_gpio(struct ltc2992_state *st)
+{
+ const char *name = dev_name(&st->client->dev);
+ char *gpio_name;
+ int ret;
+ int i;
+
+ ret = ltc2992_write_reg(st, LTC2992_GPIO_IO_CTRL, 1, 0);
+ if (ret < 0)
+ return ret;
+
+ mutex_init(&st->gpio_mutex);
+
+ for (i = 0; i < ARRAY_SIZE(st->gpio_names); i++) {
+ gpio_name = devm_kasprintf(&st->client->dev, GFP_KERNEL, "ltc2992-%x-%s",
+ st->client->addr, ltc2992_gpio_names[i]);
+ if (!gpio_name)
+ return -ENOMEM;
+
+ st->gpio_names[i] = gpio_name;
+ }
+
+ st->gc.label = name;
+ st->gc.parent = &st->client->dev;
+ st->gc.owner = THIS_MODULE;
+ st->gc.base = -1;
+ st->gc.names = st->gpio_names;
+ st->gc.ngpio = ARRAY_SIZE(st->gpio_names);
+ st->gc.get = ltc2992_gpio_get;
+ st->gc.get_multiple = ltc2992_gpio_get_multiple;
+ st->gc.set = ltc2992_gpio_set;
+ st->gc.set_multiple = ltc2992_gpio_set_multiple;
+
+ ret = devm_gpiochip_add_data(&st->client->dev, &st->gc, st);
+ if (ret)
+ dev_err(&st->client->dev, "GPIO registering failed (%d)\n", ret);
+
+ return ret;
+}
+
static umode_t ltc2992_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
int channel)
{
@@ -779,6 +933,10 @@ static int ltc2992_i2c_probe(struct i2c_client *client, const struct i2c_device_
if (ret < 0)
return ret;

+ ret = ltc2992_config_gpio(st);
+ if (ret < 0)
+ return ret;
+
hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, client->name, st,
&ltc2992_chip_info, NULL);

--
2.20.1