arm: mvebu: set 38x and 39x AVS on lower frequency

Reduce Auto Voltage Scaling VDD limit when core frequency is lower than
1600MHz. This reduces core voltage level from 1.25V to 1.15V, which
saves power.

The code is taken from Marvell's U-Boot 2013.01 revision 18.06.

Reviewed-by: Chris Packham <judge.packham@gmail.com>
Tested-by: Chris Packham <judge.packham@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stefan Roese <sr@denx.de>

diff --git a/arch/arm/mach-mvebu/include/mach/cpu.h b/arch/arm/mach-mvebu/include/mach/cpu.h
index e6140d6..2e2d72a 100644 (file)
--- a/arch/arm/mach-mvebu/include/mach/cpu.h
+++ b/arch/arm/mach-mvebu/include/mach/cpu.h
@@ -163,6 +163,13 @@ int serdes_phy_config(void);
  */
 int ddr3_init(void);
 
+/* Auto Voltage Scaling */
+#if defined(CONFIG_ARMADA_38X) || defined(CONFIG_ARMADA_39X)
+void mv_avs_init(void);
+#else
+static inline void mv_avs_init(void) {}
+#endif
+
 /*
  * get_ref_clk
  *

diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
index d387893..e9dd096 100644 (file)
--- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
+++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
@@ -256,3 +256,29 @@ u8 sys_env_device_rev_get(void)
        value = reg_read(DEV_VERSION_ID_REG);
        return (value & (REVISON_ID_MASK)) >> REVISON_ID_OFFS;
 }
+
+void mv_avs_init(void)
+{
+       u32 sar_freq;
+
+       if (!(IS_ENABLED(CONFIG_ARMADA_38X) || IS_ENABLED(CONFIG_ARMADA_39X)))
+               return;
+
+       reg_write(AVS_DEBUG_CNTR_REG, AVS_DEBUG_CNTR_DEFAULT_VALUE);
+       reg_write(AVS_DEBUG_CNTR_REG, AVS_DEBUG_CNTR_DEFAULT_VALUE);
+
+       sar_freq = reg_read(DEVICE_SAMPLE_AT_RESET1_REG);
+       sar_freq = sar_freq >> SAR_FREQ_OFFSET & SAR_FREQ_MASK;
+
+       /* Set AVS value only for core frequency of 1600MHz or less.
+        * For higher frequency leave the default value.
+        */
+       if (sar_freq <= 0xd) {
+               u32 avs_reg_data = reg_read(AVS_ENABLED_CONTROL);
+
+               avs_reg_data &= ~(AVS_LOW_VDD_LIMIT_MASK
+                               | AVS_HIGH_VDD_LIMIT_MASK);
+               avs_reg_data |= AVS_LOW_VDD_SLOW_VAL | AVS_HIGH_VDD_SLOW_VAL;
+               reg_write(AVS_ENABLED_CONTROL, avs_reg_data);
+       }
+}

diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
index 365332d..1774a5b 100644 (file)
--- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
+++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
@@ -33,6 +33,8 @@
 #define DEV_ID_REG_DEVICE_ID_OFFS      16
 #define DEV_ID_REG_DEVICE_ID_MASK      0xffff0000
 
+#define SAR_FREQ_OFFSET                        10
+#define SAR_FREQ_MASK                  0x1f
 #define SAR_DEV_ID_OFFS                        27
 #define SAR_DEV_ID_MASK                        0x7
 
@@ -155,10 +157,12 @@
 #define AVS_LOW_VDD_LIMIT_OFFS         4
 #define AVS_LOW_VDD_LIMIT_MASK         (0xff << AVS_LOW_VDD_LIMIT_OFFS)
 #define AVS_LOW_VDD_LIMIT_VAL          (0x27 << AVS_LOW_VDD_LIMIT_OFFS)
+#define AVS_LOW_VDD_SLOW_VAL           (0x23 << AVS_LOW_VDD_LIMIT_OFFS)
 
 #define AVS_HIGH_VDD_LIMIT_OFFS                12
 #define AVS_HIGH_VDD_LIMIT_MASK                (0xff << AVS_HIGH_VDD_LIMIT_OFFS)
 #define AVS_HIGH_VDD_LIMIT_VAL         (0x27 << AVS_HIGH_VDD_LIMIT_OFFS)
+#define AVS_HIGH_VDD_SLOW_VAL          (0x23 << AVS_HIGH_VDD_LIMIT_OFFS)
 
 /* Board ID numbers */
 #define MARVELL_BOARD_ID_MASK          0x10

diff --git a/arch/arm/mach-mvebu/spl.c b/arch/arm/mach-mvebu/spl.c
index d54de51..3cb27b7 100644 (file)
--- a/arch/arm/mach-mvebu/spl.c
+++ b/arch/arm/mach-mvebu/spl.c
@@ -126,6 +126,9 @@ void board_init_f(ulong dummy)
        ddr3_init();
 #endif
 
+       /* Initialize Auto Voltage Scaling */
+       mv_avs_init();
+
        /*
         * Return to the BootROM to continue the Marvell xmodem
         * UART boot protocol. As initiated by the kwboot tool.