OMAP4460: TPS Ensure SET1 is selected after voltage configuration

TPS SET0/SET1 register is selected by a GPIO pin on OMAP4460 platforms.
Currently we control this pin with a mux configuration as part of
boot sequence.
Current configuration results in the following voltage waveform:
                           |---------------| (SET1 default 1.4V)
                           |               --------(programmed voltage)
                           | <- (This switch happens on mux7,pullup)
vdd_mpu(TPS)         -----/ (OPP boot voltage)
                                             --------- (programmed voltage)
vdd_core(TWL6030)    -----------------------/ (OPP boot voltage)
Problem 1)                |<----- Tx ------>|
   timing violation for a duration Tx close to few milliseconds.
Problem 2) voltage of MPU goes beyond spec for even the highest of MPU OPP.

By using GPIO as recommended as standard procedure by TI, the sequence
changes to:
                                  -------- (programmed voltage)
vdd_mpu(TPS)         ------------/ (Opp boot voltage)
                                   --------- (programmed voltage)
vdd_core(TWL6030)    -------------/ (OPP boot voltage)

NOTE: This does not attempt to address OMAP5 - Aneesh please confirm

Reported-by: Isabelle Gros <i-gros@ti.com>
Reported-by: Jerome Angeloni <j-angeloni@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>

5 files changed, 23 insertions, 5 deletions

diff --git a/arch/arm/cpu/armv7/omap-common/clocks-common.c b/arch/arm/cpu/armv7/omap-common/clocks-common.c
index 90d3156..c02d73c 100644
--- a/arch/arm/cpu/armv7/omap-common/clocks-common.c
+++ b/arch/arm/cpu/armv7/omap-common/clocks-common.c
@@ -360,9 +360,22 @@ static void setup_non_essential_dplls(void)
 }
 #endif
 
-void do_scale_tps62361(u32 reg, u32 volt_mv)
+void do_scale_tps62361(int gpio, u32 reg, u32 volt_mv)
 {
 	u32 step;
+	int ret = 0;
+
+	/* See if we can first get the GPIO if needed */
+	if (gpio >= 0)
+		ret = gpio_request(gpio, "TPS62361_VSEL0_GPIO");
+	if (ret < 0) {
+		printf("%s: gpio %d request failed %d\n", __func__, gpio, ret);
+		gpio = -1;
+	}
+
+	/* Pull the GPIO low to select SET0 register, while we program SET1 */
+	if (gpio >= 0)
+		gpio_direction_output(gpio, 0);
 
 	step = volt_mv - TPS62361_BASE_VOLT_MV;
 	step /= 10;
@@ -370,6 +383,10 @@ void do_scale_tps62361(u32 reg, u32 volt_mv)
 	debug("do_scale_tps62361: volt - %d step - 0x%x\n", volt_mv, step);
 	if (omap_vc_bypass_send_value(TPS62361_I2C_SLAVE_ADDR, reg, step))
 		puts("Scaling voltage failed for vdd_mpu from TPS\n");
+
+	/* Pull the GPIO high to select SET1 register */
+	if (gpio >= 0)
+		gpio_direction_output(gpio, 1);
 }
 
 void do_scale_vcore(u32 vcore_reg, u32 volt_mv)
diff --git a/arch/arm/cpu/armv7/omap4/clocks.c b/arch/arm/cpu/armv7/omap4/clocks.c
index 976cfd5..1431312 100644
--- a/arch/arm/cpu/armv7/omap4/clocks.c
+++ b/arch/arm/cpu/armv7/omap4/clocks.c
@@ -281,7 +281,8 @@ void scale_vcores(void)
 	/* TPS - supplies vdd_mpu on 4460 */
 	if (omap_rev >= OMAP4460_ES1_0) {
 		volt = 1203;
-		do_scale_tps62361(TPS62361_REG_ADDR_SET1, volt);
+		do_scale_tps62361(TPS62361_VSEL0_GPIO,
+				  TPS62361_REG_ADDR_SET1, volt);
 	}
 
 	/*
diff --git a/arch/arm/cpu/armv7/omap5/clocks.c b/arch/arm/cpu/armv7/omap5/clocks.c
index 0a614f0..07a7556 100644
--- a/arch/arm/cpu/armv7/omap5/clocks.c
+++ b/arch/arm/cpu/armv7/omap5/clocks.c
@@ -247,7 +247,7 @@ void scale_vcores(void)
 
 	/* Enable 1.22V from TPS for vdd_mpu */
 	volt = 1220;
-	do_scale_tps62361(TPS62361_REG_ADDR_SET1, volt);
+	do_scale_tps62361(-1, TPS62361_REG_ADDR_SET1, volt);
 
 	/* VCORE 1 - for vdd_core */
 	volt = 1000;
diff --git a/arch/arm/include/asm/arch-omap4/clocks.h b/arch/arm/include/asm/arch-omap4/clocks.h
index 4e93950..62a339f 100644
--- a/arch/arm/include/asm/arch-omap4/clocks.h
+++ b/arch/arm/include/asm/arch-omap4/clocks.h
@@ -740,7 +740,7 @@ extern struct omap4_prcm_regs *const prcm;
 extern const u32 sys_clk_array[8];
 
 void scale_vcores(void);
-void do_scale_tps62361(u32 reg, u32 volt_mv);
+void do_scale_tps62361(int gpio, u32 reg, u32 volt_mv);
 u32 omap_ddr_clk(void);
 void do_scale_vcore(u32 vcore_reg, u32 volt_mv);
 void setup_post_dividers(u32 *const base, const struct dpll_params *params);
diff --git a/arch/arm/include/asm/arch-omap5/clocks.h b/arch/arm/include/asm/arch-omap5/clocks.h
index 28b9ff7..55145bb 100644
--- a/arch/arm/include/asm/arch-omap5/clocks.h
+++ b/arch/arm/include/asm/arch-omap5/clocks.h
@@ -686,7 +686,7 @@ extern struct omap5_prcm_regs *const prcm;
 extern const u32 sys_clk_array[8];
 
 void scale_vcores(void);
-void do_scale_tps62361(u32 reg, u32 volt_mv);
+void do_scale_tps62361(int gpio, u32 reg, u32 volt_mv);
 u32 omap_ddr_clk(void);
 void do_scale_vcore(u32 vcore_reg, u32 volt_mv);
 void setup_post_dividers(u32 *const base, const struct dpll_params *params);