4 files changed, 99 insertions, 2 deletions

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),
 };
diff --git a/drivers/clk/mvebu/armada-375.c b/drivers/clk/mvebu/armada-375.c
index c991a4d95e10..c7af2242b796 100644
--- a/drivers/clk/mvebu/armada-375.c
+++ b/drivers/clk/mvebu/armada-375.c
@@ -27,14 +27,14 @@
  * all modified at the same time, and not separately as for the Armada
  * 370 or the Armada XP SoCs.
  *
- * SAR0[21:17]   : CPU frequency    DDR frequency   L2 frequency
+ * SAR1[21:17]   : CPU frequency    DDR frequency   L2 frequency
  *               6   =  400 MHz     400 MHz         200 MHz
  *               15  =  600 MHz     600 MHz         300 MHz
  *               21  =  800 MHz     534 MHz         400 MHz
  *               25  = 1000 MHz     500 MHz         500 MHz
  *               others reserved.
  *
- * SAR0[22]   : TCLK frequency
+ * SAR1[22]   : TCLK frequency
  *               0 = 166 MHz
  *               1 = 200 MHz
  */
diff --git a/drivers/clk/mvebu/common.c b/drivers/clk/mvebu/common.c
index 8145c4efc381..7f8a33ab265b 100644
--- a/drivers/clk/mvebu/common.c
+++ b/drivers/clk/mvebu/common.c
@@ -26,8 +26,85 @@
  * Core Clocks
  */
 
+#define SSCG_CONF_MODE(reg)     (((reg) >> 16) & 0x3)
+#define SSCG_SPREAD_DOWN        0x0
+#define SSCG_SPREAD_UP          0x1
+#define SSCG_SPREAD_CENTRAL     0x2
+#define SSCG_CONF_LOW(reg)      (((reg) >> 8) & 0xFF)
+#define SSCG_CONF_HIGH(reg)     ((reg) & 0xFF)
+
 static struct clk_onecell_data clk_data;
 
+/*
+ * This function can be used by the Kirkwood, the Armada 370, the
+ * Armada XP and the Armada 375 SoC. The name of the function was
+ * chosen following the dt convention: using the first known SoC
+ * compatible with it.
+ */
+u32 kirkwood_fix_sscg_deviation(struct device_node *np, u32 system_clk)
+{
+        struct device_node *sscg_np = NULL;
+        void __iomem *sscg_map;
+        u32 sscg_reg;
+        s32 low_bound, high_bound;
+        u64 freq_swing_half;
+
+        sscg_np = of_find_node_by_name(np, "sscg");
+        if (sscg_np == NULL) {
+                pr_err("cannot get SSCG register node\n");
+                return system_clk;
+        }
+
+        sscg_map = of_iomap(sscg_np, 0);
+        if (sscg_map == NULL) {
+                pr_err("cannot map SSCG register\n");
+                goto out;
+        }
+
+        sscg_reg = readl(sscg_map);
+        high_bound = SSCG_CONF_HIGH(sscg_reg);
+        low_bound = SSCG_CONF_LOW(sscg_reg);
+
+        if ((high_bound - low_bound) <= 0)
+                goto out;
+        /*
+         * From Marvell engineer we got the following formula (when
+         * this code was written, the datasheet was erroneous)
+         * Spread percentage = 1/96 * (H - L) / H
+         * H = SSCG_High_Boundary
+         * L = SSCG_Low_Boundary
+         *
+         * As the deviation is half of spread then it lead to the
+         * following formula in the code.
+         *
+         * To avoid an overflow and not lose any significant digit in
+         * the same time we have to use a 64 bit integer.
+         */
+
+        freq_swing_half = (((u64)high_bound - (u64)low_bound)
+                        * (u64)system_clk);
+        do_div(freq_swing_half, (2 * 96 * high_bound));
+
+        switch (SSCG_CONF_MODE(sscg_reg)) {
+        case SSCG_SPREAD_DOWN:
+                system_clk -= freq_swing_half;
+                break;
+        case SSCG_SPREAD_UP:
+                system_clk += freq_swing_half;
+                break;
+        case SSCG_SPREAD_CENTRAL:
+        default:
+                break;
+        }
+
+        iounmap(sscg_map);
+
+out:
+        of_node_put(sscg_np);
+
+        return system_clk;
+}
+
 void __init mvebu_coreclk_setup(struct device_node *np,
                                 const struct coreclk_soc_desc *desc)
 {
@@ -62,6 +139,11 @@ void __init mvebu_coreclk_setup(struct device_node *np,
         of_property_read_string_index(np, "clock-output-names", 1,
                                       &cpuclk_name);
         rate = desc->get_cpu_freq(base);
+
+        if (desc->is_sscg_enabled && desc->fix_sscg_deviation
+                && desc->is_sscg_enabled(base))
+                rate = desc->fix_sscg_deviation(np, rate);
+
         clk_data.clks[1] = clk_register_fixed_rate(NULL, cpuclk_name, NULL,
                                                    CLK_IS_ROOT, rate);
         WARN_ON(IS_ERR(clk_data.clks[1]));
diff --git a/drivers/clk/mvebu/common.h b/drivers/clk/mvebu/common.h
index 8cd28e47471c..8f8db7eac3f6 100644
--- a/drivers/clk/mvebu/common.h
+++ b/drivers/clk/mvebu/common.h
@@ -30,6 +30,8 @@ struct coreclk_soc_desc {
         u32 (*get_tclk_freq)(void __iomem *sar);
         u32 (*get_cpu_freq)(void __iomem *sar);
         void (*get_clk_ratio)(void __iomem *sar, int id, int *mult, int *div);
+        bool (*is_sscg_enabled)(void __iomem *sar);
+        u32 (*fix_sscg_deviation)(struct device_node *np, u32 system_clk);
         const struct coreclk_ratio *ratios;
         int num_ratios;
 };
@@ -47,4 +49,9 @@ void __init mvebu_coreclk_setup(struct device_node *np,
 void __init mvebu_clk_gating_setup(struct device_node *np,
                                    const struct clk_gating_soc_desc *desc);
 
+/*
+ * This function is shared among the Kirkwood, Armada 370, Armada XP
+ * and Armada 375 SoC
+ */
+u32 kirkwood_fix_sscg_deviation(struct device_node *np, u32 system_clk);
 #endif