ARM: DRA7: Add support for IO delay configuration

On DRA7, in addition to the regular muxing of pins, an additional
hardware module called IODelay which is also expected to be
configured. This "IODelay" module has it's own register space that is
independent of the control module.

It is advocated strongly in TI's official documentation considering
the existing design of the DRA7 family of processors during mux or
IODelay recalibration, there is a potential for a significant glitch
which may cause functional impairment to certain hardware. It is
hence recommended to do muxing as part of IOdelay recalibration.

IODELAY recalibration sequence:
- Complete AVS voltage change on VDD_CORE_L
- Unlock IODLAY config registers.
- Perform IO delay calibration with predefined values.
- Isolate all the IOs
- Update the delay mechanism for each IO with new calibrated values.
- Configure PAD configuration registers
- De-isolate all the IOs.
- Relock IODELAY config registers.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/omap-common/clocks-common.c b/arch/arm/cpu/armv7/omap-common/clocks-common.c
index 03674e609f..fa04bbedf9 100644
--- a/arch/arm/cpu/armv7/omap-common/clocks-common.c
+++ b/arch/arm/cpu/armv7/omap-common/clocks-common.c
@@ -508,6 +508,12 @@ static u32 optimize_vcore_voltage(struct volts const *v)
 	return val;
 }
 
+#ifdef CONFIG_IODELAY_RECALIBRATION
+void __weak recalibrate_iodelay(void)
+{
+}
+#endif
+
 /*
  * Setup the voltages for the main SoC core power domains.
  * We start with the maximum voltages allowed here, as set in the corresponding
@@ -561,6 +567,16 @@ void scale_vcores(struct vcores_data const *vcores)
 
 	debug("cor: %d\n", vcores->core.value);
 	do_scale_vcore(vcores->core.addr, vcores->core.value, vcores->core.pmic);
+	/*
+	 * IO delay recalibration should be done immediately after
+	 * adjusting AVS voltages for VDD_CORE_L.
+	 * Respective boards should call __recalibrate_iodelay()
+	 * with proper mux, virtual and manual mode configurations.
+	 */
+#ifdef CONFIG_IODELAY_RECALIBRATION
+	recalibrate_iodelay();
+#endif
+
 	debug("mpu: %d\n", vcores->mpu.value);
 	do_scale_vcore(vcores->mpu.addr, vcores->mpu.value, vcores->mpu.pmic);
 	/* Configure MPU ABB LDO after scale */
@@ -587,6 +603,16 @@ void scale_vcores(struct vcores_data const *vcores)
 	val = optimize_vcore_voltage(&vcores->core);
 	do_scale_vcore(vcores->core.addr, val, vcores->core.pmic);
 
+	/*
+	 * IO delay recalibration should be done immediately after
+	 * adjusting AVS voltages for VDD_CORE_L.
+	 * Respective boards should call __recalibrate_iodelay()
+	 * with proper mux, virtual and manual mode configurations.
+	 */
+#ifdef CONFIG_IODELAY_RECALIBRATION
+	recalibrate_iodelay();
+#endif
+
 	val = optimize_vcore_voltage(&vcores->mpu);
 	do_scale_vcore(vcores->mpu.addr, val, vcores->mpu.pmic);