imx233: fix regulator voltage setting + always enable DCDC mode

Make sure DCDC is running at boot (it is disabled by default when
5V is present and we don't want to rely on the bootloader to
change this).
When changing the voltage on a regulator, it usually takes 2ms for
the voltage to stabilize. In DCDC mode, there is an irq to notify
about the event so use it ! This is especially important when
changing cpu frequency because increasing the cpu freq while the
voltage is rising is unreliable.

Change-Id: Icfe9ef3ee90156d1e17da0820d9041859f7f3bca

2 files changed, 18 insertions, 0 deletions

diff --git a/firmware/target/arm/imx233/power-imx233.c b/firmware/target/arm/imx233/power-imx233.c
index c02d6dd..186256f 100644
--- a/firmware/target/arm/imx233/power-imx233.c
+++ b/firmware/target/arm/imx233/power-imx233.c
@@ -102,6 +102,8 @@ void power_init(void)
     __FIELD_SET(HW_POWER_VDDDCTRL, LINREG_OFFSET, 2);
     __FIELD_SET(HW_POWER_VDDACTRL, LINREG_OFFSET, 2);
     __FIELD_SET(HW_POWER_VDDIOCTRL, LINREG_OFFSET, 2);
+    /* enable DCDC (more efficient) */
+    __REG_SET(HW_POWER_5VCTRL) = HW_POWER_5VCTRL__ENABLE_DCDC;
     /* enable a few bits controlling the DC-DC as recommended by Freescale */
     __REG_SET(HW_POWER_LOOPCTRL) = HW_POWER_LOOPCTRL__TOGGLE_DIF |
         HW_POWER_LOOPCTRL__EN_CM_HYST;
@@ -250,6 +252,8 @@ void imx233_power_set_regulator(enum imx233_regulator_t reg, unsigned value_mv,
     // compute raw values
     unsigned raw_val = (value_mv - regulator_info[reg].min) / regulator_info[reg].step;
     unsigned raw_bo_offset = (value_mv - brownout_mv) / regulator_info[reg].step;
+    // clear dc-dc ok flag
+    __REG_SET(HW_POWER_CTRL) = HW_POWER_CTRL__DC_OK_IRQ;
     // update
     uint32_t reg_val = (*regulator_info[reg].reg) & ~regulator_info[reg].trg_bm;
     reg_val |= raw_val << regulator_info[reg].trg_bp;
@@ -259,6 +263,17 @@ void imx233_power_set_regulator(enum imx233_regulator_t reg, unsigned value_mv,
         reg_val |= raw_bo_offset << regulator_info[reg].bo_bp;
     }
     *regulator_info[reg].reg = reg_val;
+    /* Wait until regulator is stable (ie brownout condition is gone)
+     * If DC-DC is used, we can use the DCDC_OK irq
+     * Otherwise it is unreliable (doesn't work when lowering voltage on linregs)
+     * It usually takes between 0.5ms and 2.5ms */
+    if(!(HW_POWER_5VCTRL & HW_POWER_5VCTRL__ENABLE_DCDC))
+        panicf("regulator %d: wait for voltage stabilize in linreg mode !", reg);
+    unsigned timeout = current_tick + (HZ * 20) / 1000;
+    while(!(HW_POWER_CTRL & HW_POWER_CTRL__DC_OK_IRQ) || !TIME_AFTER(current_tick, timeout))
+        yield();
+    if(!(HW_POWER_CTRL & HW_POWER_CTRL__DC_OK_IRQ))
+        panicf("regulator %d: failed to stabilize", reg);
 }
 
 // offset is -1,0 or 1
diff --git a/firmware/target/arm/imx233/power-imx233.h b/firmware/target/arm/imx233/power-imx233.h
index 6991fde..786a450 100644
--- a/firmware/target/arm/imx233/power-imx233.h
+++ b/firmware/target/arm/imx233/power-imx233.h
@@ -31,6 +31,8 @@
 #define HW_POWER_CTRL__ENIRQ_VBUS_VALID     (1 << 3)
 #define HW_POWER_CTRL__VBUSVALID_IRQ        (1 << 4)
 #define HW_POWER_CTRL__POLARITY_VBUSVALID   (1 << 5)
+#define HW_POWER_CTRL__ENIRQ_DC_OK          (1 << 14)
+#define HW_POWER_CTRL__DC_OK_IRQ            (1 << 15)
 
 #define HW_POWER_5VCTRL         (*(volatile uint32_t *)(HW_POWER_BASE + 0x10))
 #define HW_POWER_5VCTRL__ENABLE_DCDC        (1 << 0)
@@ -191,6 +193,7 @@ enum imx233_regulator_t
 void imx233_power_get_regulator(enum imx233_regulator_t reg, unsigned *target_mv,
     unsigned *brownout_mv);
 
+// WARNING this call will block until voltage is stable
 void imx233_power_set_regulator(enum imx233_regulator_t reg, unsigned target_mv,
     unsigned brownout_mv);