aspeed/scu: Introduce a aspeed_scu_get_apb_freq() routine

The APB frequency can be calculated directly when needed from the
HPLL_PARAM and CLK_SEL register values. This removes useless state in
the model.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20190904070506.1052-11-clg@kaod.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/aspeed_scu.c

@@ -164,11 +164,12 @@ static uint32_t aspeed_scu_get_random(void)
     return num;
 }
 
-static void aspeed_scu_set_apb_freq(AspeedSCUState *s)
+uint32_t aspeed_scu_get_apb_freq(AspeedSCUState *s)
 {
     AspeedSCUClass *asc = ASPEED_SCU_GET_CLASS(s);
+    uint32_t hpll = asc->calc_hpll(s, s->regs[HPLL_PARAM]);
 
-    s->apb_freq = s->hpll / (SCU_CLK_GET_PCLK_DIV(s->regs[CLK_SEL]) + 1)
+    return hpll / (SCU_CLK_GET_PCLK_DIV(s->regs[CLK_SEL]) + 1)
         / asc->apb_divider;
 }
 
@@ -228,7 +229,6 @@ static void aspeed_scu_write(void *opaque, hwaddr offset, uint64_t data,
         return;
     case CLK_SEL:
         s->regs[reg] = data;
-        aspeed_scu_set_apb_freq(s);
         break;
     case HW_STRAP1:
         if (ASPEED_IS_AST2500(s->regs[SILICON_REV])) {
@@ -290,11 +290,11 @@ static const uint32_t hpll_ast2400_freqs[][4] = {
     { 400, 375, 350, 425 }, /* 25MHz */
 };
 
-static uint32_t aspeed_2400_scu_calc_hpll(AspeedSCUState *s)
+static uint32_t aspeed_2400_scu_calc_hpll(AspeedSCUState *s, uint32_t hpll_reg)
 {
-    uint32_t hpll_reg = s->regs[HPLL_PARAM];
     uint8_t freq_select;
     bool clk_25m_in;
+    uint32_t clkin = aspeed_scu_get_clkin(s);
 
     if (hpll_reg & SCU_AST2400_H_PLL_OFF) {
         return 0;
@@ -311,7 +311,7 @@ static uint32_t aspeed_2400_scu_calc_hpll(AspeedSCUState *s)
             multiplier = (2 - od) * ((n + 2) / (d + 1));
         }
 
-        return s->clkin * multiplier;
+        return clkin * multiplier;
     }
 
     /* HW strapping */
@@ -321,10 +321,10 @@ static uint32_t aspeed_2400_scu_calc_hpll(AspeedSCUState *s)
     return hpll_ast2400_freqs[clk_25m_in][freq_select] * 1000000;
 }
 
-static uint32_t aspeed_2500_scu_calc_hpll(AspeedSCUState *s)
+static uint32_t aspeed_2500_scu_calc_hpll(AspeedSCUState *s, uint32_t hpll_reg)
 {
-    uint32_t hpll_reg   = s->regs[HPLL_PARAM];
     uint32_t multiplier = 1;
+    uint32_t clkin = aspeed_scu_get_clkin(s);
 
     if (hpll_reg & SCU_H_PLL_OFF) {
         return 0;
@@ -338,7 +338,7 @@ static uint32_t aspeed_2500_scu_calc_hpll(AspeedSCUState *s)
         multiplier = ((m + 1) / (n + 1)) / (p + 1);
     }
 
-    return s->clkin * multiplier;
+    return clkin * multiplier;
 }
 
 static void aspeed_scu_reset(DeviceState *dev)
@@ -351,13 +351,6 @@ static void aspeed_scu_reset(DeviceState *dev)
     s->regs[HW_STRAP1] = s->hw_strap1;
     s->regs[HW_STRAP2] = s->hw_strap2;
     s->regs[PROT_KEY] = s->hw_prot_key;
-
-    /*
-     * All registers are set. Now compute the frequencies of the main clocks
-     */
-    s->clkin = aspeed_scu_get_clkin(s);
-    s->hpll = asc->calc_hpll(s);
-    aspeed_scu_set_apb_freq(s);
 }
 
 static uint32_t aspeed_silicon_revs[] = {

hw/timer/aspeed_timer.c

@@ -93,7 +93,8 @@ static inline uint32_t calculate_rate(struct AspeedTimer *t)
 {
     AspeedTimerCtrlState *s = timer_to_ctrl(t);
 
-    return timer_external_clock(t) ? TIMER_CLOCK_EXT_HZ : s->scu->apb_freq;
+    return timer_external_clock(t) ? TIMER_CLOCK_EXT_HZ :
+        aspeed_scu_get_apb_freq(s->scu);
 }
 
 static inline uint32_t calculate_ticks(struct AspeedTimer *t, uint64_t now_ns)

include/hw/misc/aspeed_scu.h

@@ -32,10 +32,6 @@ typedef struct AspeedSCUState {
     uint32_t hw_strap1;
     uint32_t hw_strap2;
     uint32_t hw_prot_key;
-
-    uint32_t clkin;
-    uint32_t hpll;
-    uint32_t apb_freq;
 } AspeedSCUState;
 
 #define AST2400_A0_SILICON_REV   0x02000303U
@@ -56,12 +52,14 @@ typedef struct  AspeedSCUClass {
     SysBusDeviceClass parent_class;
 
     const uint32_t *resets;
-    uint32_t (*calc_hpll)(AspeedSCUState *s);
+    uint32_t (*calc_hpll)(AspeedSCUState *s, uint32_t hpll_reg);
     uint32_t apb_divider;
 }  AspeedSCUClass;
 
 #define ASPEED_SCU_PROT_KEY      0x1688A8A8
 
+uint32_t aspeed_scu_get_apb_freq(AspeedSCUState *s);
+
 /*
  * Extracted from Aspeed SDK v00.03.21. Fixes and extra definitions
  * were added.