mfd: dbx500: Provide a more accurate smp_twd clock

The local timer clock is based on ARM subsystem clock. This patch
obtains a more exact value of that clock by reading PRCMU registers.
Using this increases the accuracy of the local timer events.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rickard Andersson <rickard.andersson@stericsson.com>
Signed-off-by: Michel Jaouen <michel.jaouen@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c
index 7040a0081130..6b37e2d6ed8f 100644
--- a/drivers/mfd/db8500-prcmu.c
+++ b/drivers/mfd/db8500-prcmu.c
@@ -418,6 +418,9 @@ static struct {
 
 static atomic_t ac_wake_req_state = ATOMIC_INIT(0);
 
+/* Functions definition */
+static void compute_armss_rate(void);
+
 /* Spinlocks */
 static DEFINE_SPINLOCK(prcmu_lock);
 static DEFINE_SPINLOCK(clkout_lock);
@@ -517,6 +520,7 @@ static struct dsiescclk dsiescclk[3] = {
         }
 };
 
+
 /*
 * Used by MCDE to setup all necessary PRCMU registers
 */
@@ -1013,6 +1017,7 @@ int db8500_prcmu_set_arm_opp(u8 opp)
                 (mb1_transfer.ack.arm_opp != opp))
                 r = -EIO;
 
+        compute_armss_rate();
         mutex_unlock(&mb1_transfer.lock);
 
         return r;
@@ -1612,6 +1617,7 @@ static unsigned long pll_rate(void __iomem *reg, unsigned long src_rate,
         if ((branch == PLL_FIX) || ((branch == PLL_DIV) &&
                 (val & PRCM_PLL_FREQ_DIV2EN) &&
                 ((reg == PRCM_PLLSOC0_FREQ) ||
+                 (reg == PRCM_PLLARM_FREQ) ||
                  (reg == PRCM_PLLDDR_FREQ))))
                 div *= 2;
 
@@ -1661,6 +1667,39 @@ static unsigned long clock_rate(u8 clock)
         else
                 return 0;
 }
+static unsigned long latest_armss_rate;
+static unsigned long armss_rate(void)
+{
+        return latest_armss_rate;
+}
+
+static void compute_armss_rate(void)
+{
+        u32 r;
+        unsigned long rate;
+
+        r = readl(PRCM_ARM_CHGCLKREQ);
+
+        if (r & PRCM_ARM_CHGCLKREQ_PRCM_ARM_CHGCLKREQ) {
+                /* External ARMCLKFIX clock */
+
+                rate = pll_rate(PRCM_PLLDDR_FREQ, ROOT_CLOCK_RATE, PLL_FIX);
+
+                /* Check PRCM_ARM_CHGCLKREQ divider */
+                if (!(r & PRCM_ARM_CHGCLKREQ_PRCM_ARM_DIVSEL))
+                        rate /= 2;
+
+                /* Check PRCM_ARMCLKFIX_MGT divider */
+                r = readl(PRCM_ARMCLKFIX_MGT);
+                r &= PRCM_CLK_MGT_CLKPLLDIV_MASK;
+                rate /= r;
+
+        } else {/* ARM PLL */
+                rate = pll_rate(PRCM_PLLARM_FREQ, ROOT_CLOCK_RATE, PLL_DIV);
+        }
+
+        latest_armss_rate = rate;
+}
 
 static unsigned long dsiclk_rate(u8 n)
 {
@@ -1707,6 +1746,8 @@ unsigned long prcmu_clock_rate(u8 clock)
                 return pll_rate(PRCM_PLLSOC0_FREQ, ROOT_CLOCK_RATE, PLL_RAW);
         else if (clock == PRCMU_PLLSOC1)
                 return pll_rate(PRCM_PLLSOC1_FREQ, ROOT_CLOCK_RATE, PLL_RAW);
+        else if (clock == PRCMU_ARMSS)
+                return armss_rate();
         else if (clock == PRCMU_PLLDDR)
                 return pll_rate(PRCM_PLLDDR_FREQ, ROOT_CLOCK_RATE, PLL_RAW);
         else if (clock == PRCMU_PLLDSI)
@@ -2693,6 +2734,7 @@ void __init db8500_prcmu_early_init(void)
                                          handle_simple_irq);
                 set_irq_flags(irq, IRQF_VALID);
         }
+        compute_armss_rate();
 }
 
 static void __init init_prcm_registers(void)