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>

1 files changed, 81 insertions, 28 deletions

diff --git a/arch/mips/ath79/clock.c b/arch/mips/ath79/clock.c
index d2728573e9f..579f452c0b4 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)