MIPS: ath79: Fix CPU/DDR frequency calculation for SRIF PLLs

Besides the CPU and DDR PLLs, the CPU and DDR frequencies
can be derived from other PLLs in the SRIF block on the
AR934x SoCs. The current code does not checks if the SRIF
PLLs are used and this can lead to incorrectly calculated
CPU/DDR frequencies.

Fix it by calculating the frequencies from SRIF PLLs if
those are used on a given board.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: <stable@vger.kernel.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4324/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 104 insertions, 28 deletions

diff --git a/arch/mips/ath79/clock.c b/arch/mips/ath79/clock.c
index d2728573e9fc..579f452c0b45 100644
--- a/arch/mips/ath79/clock.c
+++ b/arch/mips/ath79/clock.c
@@ -17,6 +17,8 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 
+#include <asm/div64.h>
+
 #include <asm/mach-ath79/ath79.h>
 #include <asm/mach-ath79/ar71xx_regs.h>
 #include "common.h"
@@ -166,11 +168,34 @@ static void __init ar933x_clocks_init(void)
         ath79_uart_clk.rate = ath79_ref_clk.rate;
 }
 
+static u32 __init ar934x_get_pll_freq(u32 ref, u32 ref_div, u32 nint, u32 nfrac,
+                                      u32 frac, u32 out_div)
+{
+        u64 t;
+        u32 ret;
+
+        t = ath79_ref_clk.rate;
+        t *= nint;
+        do_div(t, ref_div);
+        ret = t;
+
+        t = ath79_ref_clk.rate;
+        t *= nfrac;
+        do_div(t, ref_div * frac);
+        ret += t;
+
+        ret /= (1 << out_div);
+        return ret;
+}
+
 static void __init ar934x_clocks_init(void)
 {
-        u32 pll, out_div, ref_div, nint, frac, clk_ctrl, postdiv;
+        u32 pll, out_div, ref_div, nint, nfrac, frac, clk_ctrl, postdiv;
         u32 cpu_pll, ddr_pll;
         u32 bootstrap;
+        void __iomem *dpll_base;
+
+        dpll_base = ioremap(AR934X_SRIF_BASE, AR934X_SRIF_SIZE);
 
         bootstrap = ath79_reset_rr(AR934X_RESET_REG_BOOTSTRAP);
         if (bootstrap & AR934X_BOOTSTRAP_REF_CLK_40)
@@ -178,33 +203,59 @@ static void __init ar934x_clocks_init(void)
         else
                 ath79_ref_clk.rate = 25 * 1000 * 1000;
 
-        pll = ath79_pll_rr(AR934X_PLL_CPU_CONFIG_REG);
-        out_div = (pll >> AR934X_PLL_CPU_CONFIG_OUTDIV_SHIFT) &
-                  AR934X_PLL_CPU_CONFIG_OUTDIV_MASK;
-        ref_div = (pll >> AR934X_PLL_CPU_CONFIG_REFDIV_SHIFT) &
-                  AR934X_PLL_CPU_CONFIG_REFDIV_MASK;
-        nint = (pll >> AR934X_PLL_CPU_CONFIG_NINT_SHIFT) &
-               AR934X_PLL_CPU_CONFIG_NINT_MASK;
-        frac = (pll >> AR934X_PLL_CPU_CONFIG_NFRAC_SHIFT) &
-               AR934X_PLL_CPU_CONFIG_NFRAC_MASK;
-
-        cpu_pll = nint * ath79_ref_clk.rate / ref_div;
-        cpu_pll += frac * ath79_ref_clk.rate / (ref_div * (1 << 6));
-        cpu_pll /= (1 << out_div);
-
-        pll = ath79_pll_rr(AR934X_PLL_DDR_CONFIG_REG);
-        out_div = (pll >> AR934X_PLL_DDR_CONFIG_OUTDIV_SHIFT) &
-                  AR934X_PLL_DDR_CONFIG_OUTDIV_MASK;
-        ref_div = (pll >> AR934X_PLL_DDR_CONFIG_REFDIV_SHIFT) &
-                  AR934X_PLL_DDR_CONFIG_REFDIV_MASK;
-        nint = (pll >> AR934X_PLL_DDR_CONFIG_NINT_SHIFT) &
-               AR934X_PLL_DDR_CONFIG_NINT_MASK;
-        frac = (pll >> AR934X_PLL_DDR_CONFIG_NFRAC_SHIFT) &
-               AR934X_PLL_DDR_CONFIG_NFRAC_MASK;
-
-        ddr_pll = nint * ath79_ref_clk.rate / ref_div;
-        ddr_pll += frac * ath79_ref_clk.rate / (ref_div * (1 << 10));
-        ddr_pll /= (1 << out_div);
+        pll = __raw_readl(dpll_base + AR934X_SRIF_CPU_DPLL2_REG);
+        if (pll & AR934X_SRIF_DPLL2_LOCAL_PLL) {
+                out_div = (pll >> AR934X_SRIF_DPLL2_OUTDIV_SHIFT) &
+                          AR934X_SRIF_DPLL2_OUTDIV_MASK;
+                pll = __raw_readl(dpll_base + AR934X_SRIF_CPU_DPLL1_REG);
+                nint = (pll >> AR934X_SRIF_DPLL1_NINT_SHIFT) &
+                       AR934X_SRIF_DPLL1_NINT_MASK;
+                nfrac = pll & AR934X_SRIF_DPLL1_NFRAC_MASK;
+                ref_div = (pll >> AR934X_SRIF_DPLL1_REFDIV_SHIFT) &
+                          AR934X_SRIF_DPLL1_REFDIV_MASK;
+                frac = 1 << 18;
+        } else {
+                pll = ath79_pll_rr(AR934X_PLL_CPU_CONFIG_REG);
+                out_div = (pll >> AR934X_PLL_CPU_CONFIG_OUTDIV_SHIFT) &
+                        AR934X_PLL_CPU_CONFIG_OUTDIV_MASK;
+                ref_div = (pll >> AR934X_PLL_CPU_CONFIG_REFDIV_SHIFT) &
+                          AR934X_PLL_CPU_CONFIG_REFDIV_MASK;
+                nint = (pll >> AR934X_PLL_CPU_CONFIG_NINT_SHIFT) &
+                       AR934X_PLL_CPU_CONFIG_NINT_MASK;
+                nfrac = (pll >> AR934X_PLL_CPU_CONFIG_NFRAC_SHIFT) &
+                        AR934X_PLL_CPU_CONFIG_NFRAC_MASK;
+                frac = 1 << 6;
+        }
+
+        cpu_pll = ar934x_get_pll_freq(ath79_ref_clk.rate, ref_div, nint,
+                                      nfrac, frac, out_div);
+
+        pll = __raw_readl(dpll_base + AR934X_SRIF_DDR_DPLL2_REG);
+        if (pll & AR934X_SRIF_DPLL2_LOCAL_PLL) {
+                out_div = (pll >> AR934X_SRIF_DPLL2_OUTDIV_SHIFT) &
+                          AR934X_SRIF_DPLL2_OUTDIV_MASK;
+                pll = __raw_readl(dpll_base + AR934X_SRIF_DDR_DPLL1_REG);
+                nint = (pll >> AR934X_SRIF_DPLL1_NINT_SHIFT) &
+                       AR934X_SRIF_DPLL1_NINT_MASK;
+                nfrac = pll & AR934X_SRIF_DPLL1_NFRAC_MASK;
+                ref_div = (pll >> AR934X_SRIF_DPLL1_REFDIV_SHIFT) &
+                          AR934X_SRIF_DPLL1_REFDIV_MASK;
+                frac = 1 << 18;
+        } else {
+                pll = ath79_pll_rr(AR934X_PLL_DDR_CONFIG_REG);
+                out_div = (pll >> AR934X_PLL_DDR_CONFIG_OUTDIV_SHIFT) &
+                          AR934X_PLL_DDR_CONFIG_OUTDIV_MASK;
+                ref_div = (pll >> AR934X_PLL_DDR_CONFIG_REFDIV_SHIFT) &
+                           AR934X_PLL_DDR_CONFIG_REFDIV_MASK;
+                nint = (pll >> AR934X_PLL_DDR_CONFIG_NINT_SHIFT) &
+                       AR934X_PLL_DDR_CONFIG_NINT_MASK;
+                nfrac = (pll >> AR934X_PLL_DDR_CONFIG_NFRAC_SHIFT) &
+                        AR934X_PLL_DDR_CONFIG_NFRAC_MASK;
+                frac = 1 << 10;
+        }
+
+        ddr_pll = ar934x_get_pll_freq(ath79_ref_clk.rate, ref_div, nint,
+                                      nfrac, frac, out_div);
 
         clk_ctrl = ath79_pll_rr(AR934X_PLL_CPU_DDR_CLK_CTRL_REG);
 
@@ -240,6 +291,8 @@ static void __init ar934x_clocks_init(void)
 
         ath79_wdt_clk.rate = ath79_ref_clk.rate;
         ath79_uart_clk.rate = ath79_ref_clk.rate;
+
+        iounmap(dpll_base);
 }
 
 void __init ath79_clocks_init(void)
diff --git a/arch/mips/include/asm/mach-ath79/ar71xx_regs.h b/arch/mips/include/asm/mach-ath79/ar71xx_regs.h
index 3ccae12cc7b3..a5e0f17ea77c 100644
--- a/arch/mips/include/asm/mach-ath79/ar71xx_regs.h
+++ b/arch/mips/include/asm/mach-ath79/ar71xx_regs.h
@@ -65,6 +65,8 @@
 #define AR934X_WMAC_SIZE        0x20000
 #define AR934X_EHCI_BASE        0x1b000000
 #define AR934X_EHCI_SIZE        0x200
+#define AR934X_SRIF_BASE        (AR71XX_APB_BASE + 0x00116000)
+#define AR934X_SRIF_SIZE        0x1000
 
 /*
  * DDR_CTRL block
@@ -406,4 +408,25 @@
 #define AR933X_GPIO_COUNT               30
 #define AR934X_GPIO_COUNT               23
 
+/*
+ * SRIF block
+ */
+#define AR934X_SRIF_CPU_DPLL1_REG       0x1c0
+#define AR934X_SRIF_CPU_DPLL2_REG       0x1c4
+#define AR934X_SRIF_CPU_DPLL3_REG       0x1c8
+
+#define AR934X_SRIF_DDR_DPLL1_REG       0x240
+#define AR934X_SRIF_DDR_DPLL2_REG       0x244
+#define AR934X_SRIF_DDR_DPLL3_REG       0x248
+
+#define AR934X_SRIF_DPLL1_REFDIV_SHIFT  27
+#define AR934X_SRIF_DPLL1_REFDIV_MASK   0x1f
+#define AR934X_SRIF_DPLL1_NINT_SHIFT    18
+#define AR934X_SRIF_DPLL1_NINT_MASK     0x1ff
+#define AR934X_SRIF_DPLL1_NFRAC_MASK    0x0003ffff
+
+#define AR934X_SRIF_DPLL2_LOCAL_PLL     BIT(30)
+#define AR934X_SRIF_DPLL2_OUTDIV_SHIFT  13
+#define AR934X_SRIF_DPLL2_OUTDIV_MASK   0x7
+
 #endif /* __ASM_MACH_AR71XX_REGS_H */