ENGR00125119 - Maxim 17135 display pmic: VCOM configured incorrectly

The initial VCOM voltage should be configured once.  Previously it was
left unconfigured.  Now, the VCOM value is checked the first time
through, and if it is not set correctly, it will be fixed.

Signed-off-by: Danny Nold <dannynold@freescale.com>

1 files changed, 65 insertions, 26 deletions

diff --git a/drivers/regulator/max17135-regulator.c b/drivers/regulator/max17135-regulator.c
index 8bf1c4fa5092..3fdec795fbeb 100644
--- a/drivers/regulator/max17135-regulator.c
+++ b/drivers/regulator/max17135-regulator.c
@@ -30,6 +30,12 @@
 #include <linux/gpio.h>
 
 /*
+ * Define this as 1 when using a Rev 1 MAX17135 part.  These parts have
+ * some limitations, including an inability to turn on the PMIC via I2C.
+ */
+#define MAX17135_REV 1
+
+/*
  * PMIC Register Addresses
  */
 enum {
@@ -170,11 +176,27 @@ enum {
 #define MAX17135_GVEE_MIN_VAL         0
 #define MAX17135_GVEE_MAX_VAL         1
 
+#if (MAX17135_REV == 1)
 #define MAX17135_VCOM_MIN_uV   -4325000
 #define MAX17135_VCOM_MAX_uV    -500000
 #define MAX17135_VCOM_STEP_uV     15000
 #define MAX17135_VCOM_MIN_VAL         0
 #define MAX17135_VCOM_MAX_VAL       255
+/* Required due to discrepancy between
+ * observed VCOM programming and
+ * what is suggested in the spec.
+ */
+#define MAX17135_VCOM_FUDGE_FACTOR 330000
+#else
+#define MAX17135_VCOM_MIN_uV   -3050000
+#define MAX17135_VCOM_MAX_uV    -500000
+#define MAX17135_VCOM_STEP_uV     10000
+#define MAX17135_VCOM_MIN_VAL         0
+#define MAX17135_VCOM_MAX_VAL       255
+#define MAX17135_VCOM_FUDGE_FACTOR 330000
+#endif
+
+#define MAX17135_VCOM_VOLTAGE_DEFAULT -1250000
 
 #define MAX17135_VNEG_MIN_uV    5000000
 #define MAX17135_VNEG_MAX_uV   20000000
@@ -206,17 +228,11 @@ struct max17135 {
 	int gpio_pmic_wakeup;
 	int gpio_pmic_intr;
 
+	bool vcom_setup;
+
 	int max_wait;
 };
 
-static int vcom_voltage = -1250000; /* default VCOM voltage */
-
-/*
- * Define this as 1 when using a Rev 1 MAX17135 part.  These parts have
- * some limitations, including an inability to turn on the PMIC via I2C.
- */
-#define MAX17135_REV 1
-
 /*
  * Regulator operations
  */
@@ -294,19 +310,29 @@ static int max17135_vcom_set_voltage(struct regulator_dev *reg,
 	struct max17135 *max17135 = rdev_get_drvdata(reg);
 	struct i2c_client *client = max17135->i2c_client;
 	unsigned int reg_val;
+	int vcom_read;
 
 	if ((uV < MAX17135_VCOM_MIN_uV) || (uV > MAX17135_VCOM_MAX_uV))
 		return -EINVAL;
 
-	vcom_voltage = uV;
-
 	reg_val = i2c_smbus_read_byte_data(client, REG_MAX17135_DVR);
-	reg_val &= ~BITFMASK(DVR);
-	reg_val |= BITFVAL(DVR, vcom_uV_to_rs(uV)); /* shift to correct bit */
-	i2c_smbus_write_byte_data(client, REG_MAX17135_DVR, reg_val);
 
-	reg_val = BITFVAL(CTRL_DVR, true); /* shift to correct bit */
-	return 	i2c_smbus_write_byte_data(client, REG_MAX17135_PRGM_CTRL, reg_val);
+	/*
+	 * Only program VCOM if it is not set to the desired value.
+	 * Programming VCOM excessively degrades ability to keep
+	 * DVR register value persistent.
+	 */
+	vcom_read = vcom_rs_to_uV(reg_val) - MAX17135_VCOM_FUDGE_FACTOR;
+	if (vcom_read != MAX17135_VCOM_VOLTAGE_DEFAULT) {
+		reg_val &= ~BITFMASK(DVR);
+		reg_val |= BITFVAL(DVR,
+			vcom_uV_to_rs(uV + MAX17135_VCOM_FUDGE_FACTOR));
+		i2c_smbus_write_byte_data(client, REG_MAX17135_DVR, reg_val);
+
+		reg_val = BITFVAL(CTRL_DVR, true); /* shift to correct bit */
+		return i2c_smbus_write_byte_data(client,
+			REG_MAX17135_PRGM_CTRL, reg_val);
+	}
 }
 
 static int max17135_vcom_get_voltage(struct regulator_dev *reg)
@@ -323,6 +349,19 @@ static int max17135_vcom_enable(struct regulator_dev *reg)
 {
 	struct max17135 *max17135 = rdev_get_drvdata(reg);
 
+	/*
+	 * Check to see if we need to set the VCOM voltage.
+	 * Should only be done one time. And, we can
+	 * only change vcom voltage if we have been enabled.
+	 */
+	if (!max17135->vcom_setup
+		&& gpio_get_value(max17135->gpio_pmic_pwrgood)) {
+		max17135_vcom_set_voltage(reg,
+			MAX17135_VCOM_VOLTAGE_DEFAULT,
+			MAX17135_VCOM_VOLTAGE_DEFAULT);
+		max17135->vcom_setup = true;
+	}
+
 	/* enable VCOM regulator output */
 #if (MAX17135_REV == 1)
 	gpio_set_value(max17135->gpio_pmic_vcom_ctrl, 1);
@@ -554,6 +593,15 @@ static int max17135_register_regulator(struct max17135 *max17135, int reg,
 	struct platform_device *pdev;
 	int ret;
 
+	struct i2c_client *client = max17135->i2c_client;
+	/* If we can't find PMIC via I2C, we should not register regulators */
+	if (i2c_smbus_read_byte_data(client,
+		REG_MAX17135_PRODUCT_REV >= 0)) {
+		dev_err(max17135->dev,
+			"Max17135 PMIC not found!\n");
+		return -ENXIO;
+	}
+
 	if (max17135->pdev[reg])
 		return -EBUSY;
 
@@ -610,6 +658,8 @@ static int max17135_i2c_probe(struct i2c_client *client,
 	max17135->gpio_pmic_wakeup = pdata->gpio_pmic_wakeup;
 	max17135->gpio_pmic_intr = pdata->gpio_pmic_intr;
 
+	max17135->vcom_setup = false;
+
 	ret = platform_driver_register(&max17135_regulator_driver);
 	if (ret < 0)
 		goto err;
@@ -625,17 +675,6 @@ static int max17135_i2c_probe(struct i2c_client *client,
 
 	max17135->max_wait = pdata->vpos_pwrup + pdata->vneg_pwrup +
 		pdata->gvdd_pwrup + pdata->gvee_pwrup;
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING1, pdata->gvee_pwrup);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING2, pdata->vneg_pwrup);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING3, pdata->vpos_pwrup);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING4, pdata->gvdd_pwrup);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING5, pdata->gvdd_pwrdn);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING6, pdata->vpos_pwrdn);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING7, pdata->vneg_pwrdn);
-	i2c_smbus_write_byte_data(client, REG_MAX17135_TIMING8, pdata->gvee_pwrdn);
-
-	/* save the timings to MTP on PMIC */
-	i2c_smbus_write_byte_data(client, REG_MAX17135_PRGM_CTRL, 0x02);
 
 	/* Initialize the PMIC device */
 	dev_info(&client->dev, "PMIC MAX17135 for eInk display\n");