[PATCH V2] OMAP3: PM: Set/reset T2 bit for Smartreflex on TWL.

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From: Thara Gopinath <thara@xxxxxx>

The smartreflex bit on twl4030 needs to be enabled by default irrespective
of whether smartreflex module is enabled on the OMAP side or not.
This is because without this bit enabled the voltage scaling through
vp forceupdate does not function properly on OMAP3.API added
'omap3_twl_set_sr_bit' with parameter to set/clear SR bit. It is cleared
for platforms where voltage is not scaled using vpforceupdate
or vc_bypass Method. In those cases 'omap3_twl_set_sr_bit' is called
from board file, to make sure this bit is not overwritten in
'omap3_twl_init', a flag 'twl_sr_enable'
is added.

This patch is based on LO PM Branch and Smartreflex has been
tested on OMAP3430 SDP, OMAP3630 SDP and boot tested on
OMAP2430 SDP.

Signed-off-by: Thara Gopinath <thara@xxxxxx>
Signed-off-by: Shweta Gulati <shweta.gulati@xxxxxx>
---
 arch/arm/mach-omap2/omap_twl.c |   62 ++++++++++++++++++++++++++++++++++++++++
 arch/arm/mach-omap2/pm.h       |    1 +
 2 files changed, 63 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_twl.c b/arch/arm/mach-omap2/omap_twl.c
index 00e1d2b..871a349 100644
--- a/arch/arm/mach-omap2/omap_twl.c
+++ b/arch/arm/mach-omap2/omap_twl.c
@@ -59,8 +59,15 @@
 
 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 twl_sr_enable = true;
 
+#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)
 {
@@ -269,6 +276,16 @@ int __init omap3_twl_init(void)
 		omap3_core_volt_info.vp_vddmax = OMAP3630_VP2_VLIMITTO_VDDMAX;
 	}
 
+	/*
+	 * The smartreflex bit on twl4030 needs to be enabled by
+	 * default irrespective of whether smartreflex module is
+	 * enabled on the OMAP side or not. This is because without
+	 * this bit enabled the voltage scaling through
+	 * vp forceupdate does not function properly on OMAP3.
+	 */
+	if (twl_sr_enable)
+		omap3_twl_set_sr_bit(1);
+
 	voltdm = omap_voltage_domain_lookup("mpu");
 	omap_voltage_register_pmic(voltdm, &omap3_mpu_volt_info);
 
@@ -277,3 +294,48 @@ int __init omap3_twl_init(void)
 
 	return 0;
 }
+
+/**
+ * omap3_twl_set_sr_bit() - API to Set/Clear SR bit on TWL
+ * @flag: Flag to Set/Clear SR bit
+ *
+ * If flag is non zero, enables Smartreflex bit on TWL 4030
+ * to make sure voltage scaling through Vp forceupdate 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.
+ * API returns 0 on sucess,  error is returned
+ * if I2C read/write fails.
+ */
+
+int omap3_twl_set_sr_bit(u8 flag)
+{
+	u8 temp;
+	int ret;
+
+	ret = twl_i2c_read_u8(TWL4030_MODULE_PM_RECEIVER, &temp,
+				TWL4030_DCDC_GLOBAL_CFG);
+	if (ret)
+		goto err;
+
+	if (flag) {
+		temp |= SMARTREFLEX_ENABLE;
+		twl_sr_enable = true;
+	} else {
+		temp &= ~SMARTREFLEX_ENABLE;
+		twl_sr_enable = false;
+	}
+
+	ret = twl_i2c_write_u8(TWL4030_MODULE_PM_RECEIVER, temp,
+			TWL4030_DCDC_GLOBAL_CFG);
+	if (ret) {
+err:
+		pr_err("%s: Unable to Read/Write to TWL4030 through I2C bus "
+				"\n", __func__);
+		return -EINVAL;
+	}
+	return 0;
+}
diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index 704766b..c98be66 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -127,6 +127,7 @@ static inline void omap_enable_smartreflex_on_init(void) {}
 #ifdef CONFIG_TWL4030_CORE
 extern int omap3_twl_init(void);
 extern int omap4_twl_init(void);
+extern int omap3_twl_set_sr_bit(u8 flag);
 #else
 static inline int omap3_twl_init(void)
 {
-- 
1.7.0.4

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