[PATCH v2 3/6] MIPS: ralink: add clock device providing cpu/bus clock for mt7621

Chuanhong Guo
2019-07-24T02:24:33Z

For a long time the mt7621 uses a fixed cpu clock which causes a problem
if the cpu frequency is not 880MHz.
This patch adds cpu/bus clock calculation code and binds clocks to
mt7621-pll node.

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

Signed-off-by: Weijie Gao <hackpascal@gmail.com>
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
---

Changes since v1:
1. split patch.
2. calculate clocks using the function called by CLK_OF_DECLARE
drop direct function call in timer-gic.c of ralink_clk_init
3. drop assignment of mips-hpt-frequency

arch/mips/include/asm/mach-ralink/mt7621.h | 20 ++++++
arch/mips/ralink/mt7621.c | 77 ++++++++++++++++++++++
2 files changed, 97 insertions(+)

diff --git a/arch/mips/include/asm/mach-ralink/mt7621.h b/arch/mips/include/asm/mach-ralink/mt7621.h
index 65483a4681ab..51a6e51aef3f 100644
--- a/arch/mips/include/asm/mach-ralink/mt7621.h
+++ b/arch/mips/include/asm/mach-ralink/mt7621.h
@@ -17,6 +17,10 @@
#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
@@ -24,6 +28,22 @@
#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 ba39f3f3a7c7..baf9033a67b4 100644
--- a/arch/mips/ralink/mt7621.c
+++ b/arch/mips/ralink/mt7621.c
@@ -7,12 +7,16 @@

#include <linux/kernel.h>
#include <linux/init.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>

@@ -103,11 +107,84 @@ 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;
+}
+
+static void __init mt7621_clocks_init(struct device_node *np)
+{
+ const static u32 prediv_tbl[] = {0, 1, 2, 2};
+ u32 syscfg, xtal_sel, clkcfg, clk_sel, curclk, ffiv, ffrac;
+ u32 pll, prediv, fbdiv;
+ u32 xtal_clk, cpu_clk, bus_clk;
+
+ syscfg = rt_sysc_r32(SYSC_REG_SYSTEM_CONFIG0);
+ xtal_sel = (syscfg >> XTAL_MODE_SEL_SHIFT) & XTAL_MODE_SEL_MASK;
+
+ 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:
+ cpu_clk = 500 * 1000 * 1000;
+ break;
+ case 1:
+ 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);
+
+ of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+}
+CLK_OF_DECLARE(mt7621_clk, "mediatek,mt7621-pll", mt7621_clocks_init);
+
void __init ralink_of_remap(void)
{
rt_sysc_membase = plat_of_remap_node("mtk,mt7621-sysc");
--
2.21.0