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: Tony Lindgren <tony@atomide.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/mfd/twl-core.c b/drivers/mfd/twl-core.c
index ed718328eff1..ad7d04f95dd1 100644
--- a/drivers/mfd/twl-core.c
+++ b/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) {