mfd: twl-core: Fix idle mode signaling for omaps when booted with device tree

I noticed a regression where the omap sys_clkreq signal will never
trigger for omap3 when booted with device tree while it triggers
when booted in legacy mode. This means voltage scaling does not
do anything when booted with device tree.

Turns out the reason is we fail to initialize the SmartReflex
enable bit in twl4030 with the following error:

twl: not initialized

And that happens because we are wrongly tinkering with the twl4030
registers in arch/arm/mach-omap2/omap_twl.c before the driver is
initialized. Looking at the the SmartReflex bit enable code in
omap_twl.c, we need to always set it.

So let's fix the issue by always enabling the twl4030 SmartReflex
bit in the drivers/mfd/twl-core.c probe, and drop the related
code in omap_twl.c.

Note that we still have some twl4030 tinkering left in omap_twl.c
for the twl6030 case, but that's a different patch.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

arch/arm/mach-omap2/omap_twl.c

@@ -46,15 +46,8 @@
 
 static bool is_offset_valid;
 static u8 smps_offset;
-/*
- * Flag to ensure Smartreflex bit in TWL
- * being cleared in board file is not overwritten.
- */
-static bool __initdata twl_sr_enable_autoinit;
 
-#define TWL4030_DCDC_GLOBAL_CFG        0x06
 #define REG_SMPS_OFFSET         0xE0
-#define SMARTREFLEX_ENABLE     BIT(3)
 
 static unsigned long twl4030_vsel_to_uv(const u8 vsel)
 {
@@ -251,18 +244,6 @@ int __init omap3_twl_init(void)
 	if (!cpu_is_omap34xx())
 		return -ENODEV;
 
-	/*
-	 * The smartreflex bit on twl4030 specifies if the setting of voltage
-	 * is done over the I2C_SR path. Since this setting is independent of
-	 * the actual usage of smartreflex AVS module, we enable TWL SR bit
-	 * by default irrespective of whether smartreflex AVS module is enabled
-	 * on the OMAP side or not. This is because without this bit enabled,
-	 * the voltage scaling through vp forceupdate/bypass mechanism of
-	 * voltage scaling will not function on TWL over I2C_SR.
-	 */
-	if (!twl_sr_enable_autoinit)
-		omap3_twl_set_sr_bit(true);
-
 	voltdm = voltdm_lookup("mpu_iva");
 	omap_voltage_register_pmic(voltdm, &omap3_mpu_pmic);
 
@@ -271,44 +252,3 @@ int __init omap3_twl_init(void)
 
 	return 0;
 }
-
-/**
- * omap3_twl_set_sr_bit() - Set/Clear SR bit on TWL
- * @enable: enable SR mode in twl or not
- *
- * If 'enable' is true, enables Smartreflex bit on TWL 4030 to make sure
- * voltage scaling through OMAP SR works. Else, the smartreflex bit
- * on twl4030 is cleared as there are platforms which use OMAP3 and T2 but
- * use Synchronized Scaling Hardware Strategy (ENABLE_VMODE=1) and Direct
- * Strategy Software Scaling Mode (ENABLE_VMODE=0), for setting the voltages,
- * in those scenarios this bit is to be cleared (enable = false).
- *
- * Returns 0 on success, error is returned if I2C read/write fails.
- */
-int __init omap3_twl_set_sr_bit(bool enable)
-{
-	u8 temp;
-	int ret;
-	if (twl_sr_enable_autoinit)
-		pr_warning("%s: unexpected multiple calls\n", __func__);
-
-	ret = twl_i2c_read_u8(TWL_MODULE_PM_RECEIVER, &temp,
-			      TWL4030_DCDC_GLOBAL_CFG);
-	if (ret)
-		goto err;
-
-	if (enable)
-		temp |= SMARTREFLEX_ENABLE;
-	else
-		temp &= ~SMARTREFLEX_ENABLE;
-
-	ret = twl_i2c_write_u8(TWL_MODULE_PM_RECEIVER, temp,
-			       TWL4030_DCDC_GLOBAL_CFG);
-	if (!ret) {
-		twl_sr_enable_autoinit = true;
-		return 0;
-	}
-err:
-	pr_err("%s: Error access to TWL4030 (%d)\n", __func__, ret);
-	return ret;
-}

drivers/mfd/twl-core.c

@@ -98,7 +98,11 @@
 #define TWL4030_BASEADD_BACKUP		0x0014
 #define TWL4030_BASEADD_INT		0x002E
 #define TWL4030_BASEADD_PM_MASTER	0x0036
+
 #define TWL4030_BASEADD_PM_RECEIVER	0x005B
+#define TWL4030_DCDC_GLOBAL_CFG		0x06
+#define SMARTREFLEX_ENABLE		BIT(3)
+
 #define TWL4030_BASEADD_RTC		0x001C
 #define TWL4030_BASEADD_SECURED_REG	0x0000
 
@@ -1204,6 +1208,11 @@ twl_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	 * Disable TWL4030/TWL5030 I2C Pull-up on I2C1 and I2C4(SR) interface.
 	 * Program I2C_SCL_CTRL_PU(bit 0)=0, I2C_SDA_CTRL_PU (bit 2)=0,
 	 * SR_I2C_SCL_CTRL_PU(bit 4)=0 and SR_I2C_SDA_CTRL_PU(bit 6)=0.
+	 *
+	 * Also, always enable SmartReflex bit as that's needed for omaps to
+	 * to do anything over I2C4 for voltage scaling even if SmartReflex
+	 * is disabled. Without the SmartReflex bit omap sys_clkreq idle
+	 * signal will never trigger for retention idle.
 	 */
 	if (twl_class_is_4030()) {
 		u8 temp;
@@ -1212,6 +1221,12 @@ twl_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		temp &= ~(SR_I2C_SDA_CTRL_PU | SR_I2C_SCL_CTRL_PU | \
 			I2C_SDA_CTRL_PU | I2C_SCL_CTRL_PU);
 		twl_i2c_write_u8(TWL4030_MODULE_INTBR, temp, REG_GPPUPDCTR1);
+
+		twl_i2c_read_u8(TWL_MODULE_PM_RECEIVER, &temp,
+				TWL4030_DCDC_GLOBAL_CFG);
+		temp |= SMARTREFLEX_ENABLE;
+		twl_i2c_write_u8(TWL_MODULE_PM_RECEIVER, temp,
+				 TWL4030_DCDC_GLOBAL_CFG);
 	}
 
 	if (node) {