clk: clk_stm32h7: Fix stm32_clk_get_rate() for timer

For timer clock, an additional prescaler is used which
was not taken into account previously.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>

diff --git a/drivers/clk/clk_stm32h7.c b/drivers/clk/clk_stm32h7.c
index c9594d405a0c8d3c6f9accd8d455f8ef33476bf6..92db71431e45791cac86f83c1c43f7a0d9c10d2d 100644 (file)
--- a/drivers/clk/clk_stm32h7.c
+++ b/drivers/clk/clk_stm32h7.c
@@ -35,6 +35,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #define RCC_CFGR_SW_CSI                        1
 #define RCC_CFGR_SW_HSE                        2
 #define RCC_CFGR_SW_PLL1               3
+#define RCC_CFGR_TIMPRE                        BIT(15)
 
 #define RCC_PLLCKSELR_PLLSRC_HSI       0
 #define RCC_PLLCKSELR_PLLSRC_CSI       1
@@ -339,6 +340,11 @@ struct pll_psc sys_pll_psc = {
        .divr = 2,
 };
 
+enum apb {
+       APB1,
+       APB2,
+};
+
 int configure_clocks(struct udevice *dev)
 {
        struct stm32_clk *priv = dev_get_priv(dev);
@@ -562,6 +568,67 @@ static u32 stm32_get_PLL1_rate(struct stm32_rcc_regs *regs,
        return -EINVAL;
 }
 
+static u32 stm32_get_apb_psc(struct stm32_rcc_regs *regs, enum apb apb)
+{
+       u16 prescaler_table[8] = {2, 4, 8, 16, 64, 128, 256, 512};
+       u32 d2cfgr = readl(&regs->d2cfgr);
+
+       if (apb == APB1) {
+               if (d2cfgr & RCC_D2CFGR_D2PPRE1_DIVIDED)
+                       /* get D2 domain APB1 prescaler */
+                       return prescaler_table[
+                               ((d2cfgr & RCC_D2CFGR_D2PPRE1_DIVIDER)
+                               >> RCC_D2CFGR_D2PPRE1_SHIFT)];
+       } else  { /* APB2 */
+               if (d2cfgr & RCC_D2CFGR_D2PPRE2_DIVIDED)
+                       /* get D2 domain APB2 prescaler */
+                       return prescaler_table[
+                               ((d2cfgr & RCC_D2CFGR_D2PPRE2_DIVIDER)
+                               >> RCC_D2CFGR_D2PPRE2_SHIFT)];
+       }
+
+       return 1;
+};
+
+static u32 stm32_get_timer_rate(struct stm32_clk *priv, u32 sysclk,
+                               enum apb apb)
+{
+       struct stm32_rcc_regs *regs = priv->rcc_base;
+u32 psc = stm32_get_apb_psc(regs, apb);
+
+       if (readl(&regs->cfgr) & RCC_CFGR_TIMPRE)
+               /*
+                * if APB prescaler is configured to a
+                * division factor of 1, 2 or 4
+                */
+               switch (psc) {
+               case 1:
+               case 2:
+               case 4:
+                       return sysclk;
+               case 8:
+                       return sysclk / 2;
+               case 16:
+                       return sysclk / 4;
+               default:
+                       pr_err("unexpected prescaler value (%d)\n", psc);
+                       return 0;
+               }
+       else
+               switch (psc) {
+               case 1:
+                       return sysclk;
+               case 2:
+               case 4:
+               case 8:
+               case 16:
+                       return sysclk / psc;
+               default:
+                       pr_err("unexpected prescaler value (%d)\n", psc);
+                       return 0;
+               }
+};
+
 static ulong stm32_clk_get_rate(struct clk *clk)
 {
        struct stm32_clk *priv = dev_get_priv(clk->dev);
@@ -660,31 +727,42 @@ static ulong stm32_clk_get_rate(struct clk *clk)
 
        case RCC_APB1LENR:
        case RCC_APB1HENR:
-               if (d1cfgr & RCC_D2CFGR_D2PPRE1_DIVIDED) {
-                       /* get D2 domain APB1 prescaler */
-                       idx = (d1cfgr & RCC_D2CFGR_D2PPRE1_DIVIDER) >>
-                             RCC_D2CFGR_D2PPRE1_SHIFT;
-                       sysclk = sysclk / prescaler_table[idx];
+               /* special case for GPT timers */
+               switch (clk->id) {
+               case TIM14_CK:
+               case TIM13_CK:
+               case TIM12_CK:
+               case TIM7_CK:
+               case TIM6_CK:
+               case TIM5_CK:
+               case TIM4_CK:
+               case TIM3_CK:
+               case TIM2_CK:
+                       return stm32_get_timer_rate(priv, sysclk, APB1);
                }
 
                debug("%s system clock: freq after APB1 prescaler = %ld\n",
                      __func__, sysclk);
 
-               return sysclk;
+               return (sysclk / stm32_get_apb_psc(regs, APB1));
                break;
 
        case RCC_APB2ENR:
-               if (d1cfgr & RCC_D2CFGR_D2PPRE2_DIVIDED) {
-                       /* get D2 domain APB1 prescaler */
-                       idx = (d1cfgr & RCC_D2CFGR_D2PPRE2_DIVIDER) >>
-                             RCC_D2CFGR_D2PPRE2_SHIFT;
-                       sysclk = sysclk / prescaler_table[idx];
+               /* special case for timers */
+               switch (clk->id) {
+               case TIM17_CK:
+               case TIM16_CK:
+               case TIM15_CK:
+               case TIM8_CK:
+               case TIM1_CK:
+                       return stm32_get_timer_rate(priv, sysclk, APB2);
                }
 
                debug("%s system clock: freq after APB2 prescaler = %ld\n",
                      __func__, sysclk);
 
-               return sysclk;
+               return (sysclk / stm32_get_apb_psc(regs, APB2));
+
                break;
 
        default: