pm2301: LPN mode control support

The AC charger plug-in detection while booting causes I2C read
failure if AC charger is not connected. Now the LPN pin is enabled
for every PM2301 register access, which solves the issue.

Signed-off-by: Rupesh Kumar <rupesh.kumar@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: Vijaya Kumar K-1 <vijay.kilari@stericsson.com>
Reviewed-by: Rabin VINCENT <rabin.vincent@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Tested-by: Jonas ABERG <jonas.aberg@stericsson.com>

3 files changed, 71 insertions, 2 deletions

diff --git a/drivers/power/pm2301_charger.c b/drivers/power/pm2301_charger.c
index 9b2e8943f944..ed48d75bb786 100644
--- a/drivers/power/pm2301_charger.c
+++ b/drivers/power/pm2301_charger.c
@@ -28,6 +28,7 @@
 #include <linux/mfd/abx500/ab8500-gpadc.h>
 #include <linux/mfd/abx500/ux500_chargalg.h>
 #include <linux/pm2301_charger.h>
+#include <linux/gpio.h>
 
 #include "pm2301_charger.h"
 
@@ -110,9 +111,35 @@ static const struct i2c_device_id pm2xxx_ident[] = {
         { }
 };
 
+static void set_lpn_pin(struct pm2xxx_charger *pm2)
+{
+        if (pm2->ac.charger_connected)
+                return;
+        gpio_set_value(pm2->lpn_pin, 1);
+
+        return;
+}
+
+static void clear_lpn_pin(struct pm2xxx_charger *pm2)
+{
+        if (pm2->ac.charger_connected)
+                return;
+        gpio_set_value(pm2->lpn_pin, 0);
+
+        return;
+}
+
 static int pm2xxx_reg_read(struct pm2xxx_charger *pm2, int reg, u8 *val)
 {
         int ret;
+        /*
+         * When AC adaptor is unplugged, the host
+         * must put LPN high to be able to
+         * communicate by I2C with PM2301
+         * and receive I2C "acknowledge" from PM2301.
+         */
+        mutex_lock(&pm2->lock);
+        set_lpn_pin(pm2);
 
         ret = i2c_smbus_read_i2c_block_data(pm2->config.pm2xxx_i2c, reg,
                                 1, val);
@@ -120,6 +147,8 @@ static int pm2xxx_reg_read(struct pm2xxx_charger *pm2, int reg, u8 *val)
                 dev_err(pm2->dev, "Error reading register at 0x%x\n", reg);
         else
                 ret = 0;
+        clear_lpn_pin(pm2);
+        mutex_unlock(&pm2->lock);
 
         return ret;
 }
@@ -127,6 +156,14 @@ static int pm2xxx_reg_read(struct pm2xxx_charger *pm2, int reg, u8 *val)
 static int pm2xxx_reg_write(struct pm2xxx_charger *pm2, int reg, u8 val)
 {
         int ret;
+        /*
+         * When AC adaptor is unplugged, the host
+         * must put LPN high to be able to
+         * communicate by I2C with PM2301
+         * and receive I2C "acknowledge" from PM2301.
+         */
+        mutex_lock(&pm2->lock);
+        set_lpn_pin(pm2);
 
         ret = i2c_smbus_write_i2c_block_data(pm2->config.pm2xxx_i2c, reg,
                                 1, &val);
@@ -134,6 +171,8 @@ static int pm2xxx_reg_write(struct pm2xxx_charger *pm2, int reg, u8 val)
                 dev_err(pm2->dev, "Error writing register at 0x%x\n", reg);
         else
                 ret = 0;
+        clear_lpn_pin(pm2);
+        mutex_unlock(&pm2->lock);
 
         return ret;
 }
@@ -850,6 +889,14 @@ static int __devinit pm2xxx_wall_charger_probe(struct i2c_client *i2c_client,
 
         pm2->bat = pl_data->battery;
 
+        /*get lpn GPIO from platform data*/
+        if (!pm2->pdata->lpn_gpio) {
+                dev_err(pm2->dev, "no lpn gpio data supplied\n");
+                ret = -EINVAL;
+                goto free_device_info;
+        }
+        pm2->lpn_pin = pm2->pdata->lpn_gpio;
+
         if (!i2c_check_functionality(i2c_client->adapter,
                         I2C_FUNC_SMBUS_BYTE_DATA |
                         I2C_FUNC_SMBUS_READ_WORD_DATA)) {
@@ -929,10 +976,25 @@ static int __devinit pm2xxx_wall_charger_probe(struct i2c_client *i2c_client,
                 goto unregister_pm2xxx_charger;
         }
 
+        /*Initialize lock*/
+        mutex_init(&pm2->lock);
+
         /*
-         * I2C Read/Write will fail, if AC adaptor is not connected.
-         * fix the charger detection mechanism.
+         * Charger detection mechanism requires pulling up the LPN pin
+         * while i2c communication if Charger is not connected
+         * LPN pin of PM2301 is GPIO60 of AB9540
          */
+        ret = gpio_request(pm2->lpn_pin, "pm2301_lpm_gpio");
+        if (ret < 0) {
+                dev_err(pm2->dev, "pm2301_lpm_gpio request failed\n");
+                goto unregister_pm2xxx_charger;
+        }
+        ret = gpio_direction_output(pm2->lpn_pin, 0);
+        if (ret < 0) {
+                dev_err(pm2->dev, "pm2301_lpm_gpio direction failed\n");
+                goto free_gpio;
+        }
+
         ret = pm2xxx_charger_detection(pm2, &val);
 
         if ((ret == 0) && val) {
@@ -944,6 +1006,8 @@ static int __devinit pm2xxx_wall_charger_probe(struct i2c_client *i2c_client,
 
         return 0;
 
+free_gpio:
+        gpio_free(pm2->lpn_pin);
 unregister_pm2xxx_charger:
         /* unregister power supply */
         power_supply_unregister(&pm2->ac_chg.psy);
@@ -977,6 +1041,9 @@ static int __devexit pm2xxx_wall_charger_remove(struct i2c_client *i2c_client)
 
         power_supply_unregister(&pm2->ac_chg.psy);
 
+        /*Free GPIO60*/
+        gpio_free(pm2->lpn_pin);
+
         kfree(pm2);
 
         return 0;
diff --git a/drivers/power/pm2301_charger.h b/drivers/power/pm2301_charger.h
index 3531cc5a9056..e6319cdbc94f 100644
--- a/drivers/power/pm2301_charger.h
+++ b/drivers/power/pm2301_charger.h
@@ -493,6 +493,7 @@ struct pm2xxx_charger {
         int old_vbat;
         int failure_case;
         int failure_input_ovv;
+        unsigned int lpn_pin;
         struct pm2xxx_interrupts *pm2_int;
         struct ab8500_gpadc *gpadc;
         struct regulator *regu;
diff --git a/include/linux/pm2301_charger.h b/include/linux/pm2301_charger.h
index 16bb1d34b9d5..fc3f026922ae 100644
--- a/include/linux/pm2301_charger.h
+++ b/include/linux/pm2301_charger.h
@@ -49,6 +49,7 @@ struct pm2xxx_charger_platform_data {
         int i2c_bus;
         const char *label;
         int irq_number;
+        unsigned int lpn_gpio;
         int irq_type;
 };