[PATCH V2 2/4] clk: mvebu: armada-370: Fix timer drift caused by the SSCG deviation

Gregory CLEMENT
2014-09-02T08:15:17Z

This commit activates the SSCG deviation correction for the Armada
370. It uses the optional function introduced by the commit "clk:
mvebu: Fix clk frequency value if SSCG is enabled".

Without this fix the deviation measured on a Mirabox was of a few
second each hour, whereas with this fix it was reduced at around
50ppm (around 4s per day).

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
drivers/clk/mvebu/armada-370.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/clk/mvebu/armada-370.c b/drivers/clk/mvebu/armada-370.c
index bef198a83863..756f0f39d6a3 100644
--- a/drivers/clk/mvebu/armada-370.c
+++ b/drivers/clk/mvebu/armada-370.c
@@ -23,6 +23,7 @@
*/

#define SARL 0 /* Low part [0:31] */
+#define SARL_A370_SSCG_ENABLE BIT(10)
#define SARL_A370_PCLK_FREQ_OPT 11
#define SARL_A370_PCLK_FREQ_OPT_MASK 0xF
#define SARL_A370_FAB_FREQ_OPT 15
@@ -133,10 +134,17 @@ static void __init a370_get_clk_ratio(
}
}

+static bool a370_is_sscg_enabled(void __iomem *sar)
+{
+ return !(readl(sar) & SARL_A370_SSCG_ENABLE);
+}
+
static const struct coreclk_soc_desc a370_coreclks = {
.get_tclk_freq = a370_get_tclk_freq,
.get_cpu_freq = a370_get_cpu_freq,
.get_clk_ratio = a370_get_clk_ratio,
+ .is_sscg_enabled = a370_is_sscg_enabled,
+ .fix_sscg_deviation = kirkwood_fix_sscg_deviation,
.ratios = a370_coreclk_ratios,
.num_ratios = ARRAY_SIZE(a370_coreclk_ratios),
};
--
1.9.1