For a long time the mt7621 uses a fixed cpu clock which causes a problem
if the cpu frequency is not 880MHz.

This patch fixes the cpu clock calculation and adds the cpu/bus clkdev
which will be used in dts.

Signed-off-by: Weijie Gao <hackpas...@gmail.com>

Ported from OpenWrt:
c7ca224299 ramips: fix cpu clock of mt7621 and add dt clk devices

Signed-off-by: Chuanhong Guo <gch981...@gmail.com>
---

Resend due to incorrect patch subject.

 arch/mips/include/asm/mach-ralink/mt7621.h |  20 ++++
 arch/mips/ralink/mt7621.c                  | 102 ++++++++++++++-------
 arch/mips/ralink/timer-gic.c               |   4 +-
 3 files changed, 93 insertions(+), 33 deletions(-)

diff --git a/arch/mips/include/asm/mach-ralink/mt7621.h 
b/arch/mips/include/asm/mach-ralink/mt7621.h
index a672e06fa5fd..b8a8834164c8 100644
--- a/arch/mips/include/asm/mach-ralink/mt7621.h
+++ b/arch/mips/include/asm/mach-ralink/mt7621.h
@@ -19,6 +19,10 @@
 #define SYSC_REG_CHIP_REV              0x0c
 #define SYSC_REG_SYSTEM_CONFIG0                0x10
 #define SYSC_REG_SYSTEM_CONFIG1                0x14
+#define SYSC_REG_CLKCFG0               0x2c
+#define SYSC_REG_CUR_CLK_STS           0x44
+
+#define MEMC_REG_CPU_PLL               0x648
 
 #define CHIP_REV_PKG_MASK              0x1
 #define CHIP_REV_PKG_SHIFT             16
@@ -26,6 +30,22 @@
 #define CHIP_REV_VER_SHIFT             8
 #define CHIP_REV_ECO_MASK              0xf
 
+#define XTAL_MODE_SEL_MASK             0x7
+#define XTAL_MODE_SEL_SHIFT            6
+
+#define CPU_CLK_SEL_MASK               0x3
+#define CPU_CLK_SEL_SHIFT              30
+
+#define CUR_CPU_FDIV_MASK              0x1f
+#define CUR_CPU_FDIV_SHIFT             8
+#define CUR_CPU_FFRAC_MASK             0x1f
+#define CUR_CPU_FFRAC_SHIFT            0
+
+#define CPU_PLL_PREDIV_MASK            0x3
+#define CPU_PLL_PREDIV_SHIFT           12
+#define CPU_PLL_FBDIV_MASK             0x7f
+#define CPU_PLL_FBDIV_SHIFT            4
+
 #define MT7621_DRAM_BASE                0x0
 #define MT7621_DDR2_SIZE_MIN           32
 #define MT7621_DDR2_SIZE_MAX           256
diff --git a/arch/mips/ralink/mt7621.c b/arch/mips/ralink/mt7621.c
index d2718de60b9b..0b2845a4a036 100644
--- a/arch/mips/ralink/mt7621.c
+++ b/arch/mips/ralink/mt7621.c
@@ -9,22 +9,22 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <dt-bindings/clock/mt7621-clk.h>
 
 #include <asm/mipsregs.h>
 #include <asm/smp-ops.h>
 #include <asm/mips-cps.h>
 #include <asm/mach-ralink/ralink_regs.h>
 #include <asm/mach-ralink/mt7621.h>
+#include <asm/time.h>
 
 #include <pinmux.h>
 
 #include "common.h"
 
-#define SYSC_REG_SYSCFG                0x10
-#define SYSC_REG_CPLL_CLKCFG0  0x2c
-#define SYSC_REG_CUR_CLK_STS   0x44
-#define CPU_CLK_SEL            (BIT(30) | BIT(31))
-
 #define MT7621_GPIO_MODE_UART1         1
 #define MT7621_GPIO_MODE_I2C           2
 #define MT7621_GPIO_MODE_UART3_MASK    0x3
@@ -110,49 +110,90 @@ static struct rt2880_pmx_group mt7621_pinmux_data[] = {
        { 0 }
 };
 
+static struct clk *clks[MT7621_CLK_MAX];
+static struct clk_onecell_data clk_data = {
+       .clks = clks,
+       .clk_num = ARRAY_SIZE(clks),
+};
+
 phys_addr_t mips_cpc_default_phys_base(void)
 {
        panic("Cannot detect cpc address");
 }
 
+static struct clk *__init mt7621_add_sys_clkdev(
+       const char *id, unsigned long rate)
+{
+       struct clk *clk;
+       int err;
+
+       clk = clk_register_fixed_rate(NULL, id, NULL, 0, rate);
+       if (IS_ERR(clk))
+               panic("failed to allocate %s clock structure", id);
+
+       err = clk_register_clkdev(clk, id, NULL);
+       if (err)
+               panic("unable to register %s clock device", id);
+
+       return clk;
+}
+
 void __init ralink_clk_init(void)
 {
-       int cpu_fdiv = 0;
-       int cpu_ffrac = 0;
-       int fbdiv = 0;
-       u32 clk_sts, syscfg;
-       u8 clk_sel = 0, xtal_mode;
-       u32 cpu_clk;
+       u32 syscfg, xtal_sel, clkcfg, clk_sel, curclk, ffiv, ffrac;
+       u32 pll, prediv, fbdiv;
+       u32 xtal_clk, cpu_clk, bus_clk;
+
+       const static u32 prediv_tbl[] = {0, 1, 2, 2};
+
+       syscfg = rt_sysc_r32(SYSC_REG_SYSTEM_CONFIG0);
+       xtal_sel = (syscfg >> XTAL_MODE_SEL_SHIFT) & XTAL_MODE_SEL_MASK;
 
-       if ((rt_sysc_r32(SYSC_REG_CPLL_CLKCFG0) & CPU_CLK_SEL) != 0)
-               clk_sel = 1;
+       clkcfg = rt_sysc_r32(SYSC_REG_CLKCFG0);
+       clk_sel = (clkcfg >> CPU_CLK_SEL_SHIFT) & CPU_CLK_SEL_MASK;
+
+       curclk = rt_sysc_r32(SYSC_REG_CUR_CLK_STS);
+       ffiv = (curclk >> CUR_CPU_FDIV_SHIFT) & CUR_CPU_FDIV_MASK;
+       ffrac = (curclk >> CUR_CPU_FFRAC_SHIFT) & CUR_CPU_FFRAC_MASK;
+
+       if (xtal_sel <= 2)
+               xtal_clk = 20 * 1000 * 1000;
+       else if (xtal_sel <= 5)
+               xtal_clk = 40 * 1000 * 1000;
+       else
+               xtal_clk = 25 * 1000 * 1000;
 
        switch (clk_sel) {
        case 0:
-               clk_sts = rt_sysc_r32(SYSC_REG_CUR_CLK_STS);
-               cpu_fdiv = ((clk_sts >> 8) & 0x1F);
-               cpu_ffrac = (clk_sts & 0x1F);
-               cpu_clk = (500 * cpu_ffrac / cpu_fdiv) * 1000 * 1000;
+               cpu_clk = 500 * 1000 * 1000;
                break;
-
        case 1:
-               fbdiv = ((rt_sysc_r32(0x648) >> 4) & 0x7F) + 1;
-               syscfg = rt_sysc_r32(SYSC_REG_SYSCFG);
-               xtal_mode = (syscfg >> 6) & 0x7;
-               if (xtal_mode >= 6) {
-                       /* 25Mhz Xtal */
-                       cpu_clk = 25 * fbdiv * 1000 * 1000;
-               } else if (xtal_mode >= 3) {
-                       /* 40Mhz Xtal */
-                       cpu_clk = 40 * fbdiv * 1000 * 1000;
-               } else {
-                       /* 20Mhz Xtal */
-                       cpu_clk = 20 * fbdiv * 1000 * 1000;
-               }
+               pll = rt_memc_r32(MEMC_REG_CPU_PLL);
+               fbdiv = (pll >> CPU_PLL_FBDIV_SHIFT) & CPU_PLL_FBDIV_MASK;
+               prediv = (pll >> CPU_PLL_PREDIV_SHIFT) & CPU_PLL_PREDIV_MASK;
+               cpu_clk = ((fbdiv + 1) * xtal_clk) >> prediv_tbl[prediv];
                break;
+       default:
+               cpu_clk = xtal_clk;
        }
+
+       cpu_clk = cpu_clk / ffiv * ffrac;
+       bus_clk = cpu_clk / 4;
+
+       clks[MT7621_CLK_CPU] = mt7621_add_sys_clkdev("cpu", cpu_clk);
+       clks[MT7621_CLK_BUS] = mt7621_add_sys_clkdev("bus", bus_clk);
+
+       pr_info("CPU Clock: %dMHz\n", cpu_clk / 1000000);
+       mips_hpt_frequency = cpu_clk / 2;
 }
 
+static void __init mt7621_clocks_init_dt(struct device_node *np)
+{
+       of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+}
+
+CLK_OF_DECLARE(mt7621_clk, "mediatek,mt7621-pll", mt7621_clocks_init_dt);
+
 void __init ralink_of_remap(void)
 {
        rt_sysc_membase = plat_of_remap_node("mtk,mt7621-sysc");
diff --git a/arch/mips/ralink/timer-gic.c b/arch/mips/ralink/timer-gic.c
index b5f07d21fcf2..4fed842ae8eb 100644
--- a/arch/mips/ralink/timer-gic.c
+++ b/arch/mips/ralink/timer-gic.c
@@ -11,14 +11,14 @@
 
 #include <linux/of.h>
 #include <linux/clk-provider.h>
-#include <linux/clocksource.h>
+#include <asm/time.h>
 
 #include "common.h"
 
 void __init plat_time_init(void)
 {
        ralink_of_remap();
-
+       ralink_clk_init();
        of_clk_init(NULL);
        timer_probe();
 }
-- 
2.21.0

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