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Subject[PATCH v4 2/5] clk: aspeed: Register core clocks
Date
This registers the core clocks; those which are required to calculate
the rate of the timer peripheral so the system can load a clocksource
driver.

Signed-off-by: Joel Stanley <joel@jms.id.au>

---
v4:
- Add defines to document the BIT() macros
v3:
- Fix ast2400 ahb calculation
- Remove incorrect 'this is wrong' comment
- Separate out clkin calc to be per platform
- Support 48MHz clkin on ast2400
---
drivers/clk/clk-aspeed.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 177 insertions(+)

diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
index a45eb351bb05..d39cf51a5114 100644
--- a/drivers/clk/clk-aspeed.c
+++ b/drivers/clk/clk-aspeed.c
@@ -20,7 +20,23 @@

#include <dt-bindings/clock/aspeed-clock.h>

+#define ASPEED_RESET_CTRL 0x04
+#define ASPEED_CLK_SELECTION 0x08
+#define ASPEED_CLK_STOP_CTRL 0x0c
+#define ASPEED_MPLL_PARAM 0x20
+#define ASPEED_HPLL_PARAM 0x24
+#define AST2500_HPLL_BYPASS_EN BIT(20)
+#define AST2400_HPLL_STRAPPED BIT(18)
+#define AST2400_HPLL_BYPASS_EN BIT(17)
+#define ASPEED_MISC_CTRL 0x2c
+#define UART_DIV13_EN BIT(12)
#define ASPEED_STRAP 0x70
+#define CLKIN_25MHZ_EN BIT(23)
+#define AST2400_CLK_SOURCE_SEL BIT(18)
+#define ASPEED_CLK_SELECTION_2 0xd8
+
+/* Globally visible clocks */
+static DEFINE_SPINLOCK(aspeed_clk_lock);

/* Keeps track of all clocks */
static struct clk_hw_onecell_data *aspeed_clk_data;
@@ -98,6 +114,160 @@ static const struct aspeed_gate_data aspeed_gates[] __initconst = {
[ASPEED_CLK_GATE_LHCCLK] = { 28, -1, "lhclk-gate", "lhclk", 0 }, /* LPC master/LPC+ */
};

+static const struct clk_div_table ast2400_div_table[] = {
+ { 0x0, 2 },
+ { 0x1, 4 },
+ { 0x2, 6 },
+ { 0x3, 8 },
+ { 0x4, 10 },
+ { 0x5, 12 },
+ { 0x6, 14 },
+ { 0x7, 16 },
+ { 0 }
+};
+
+static const struct clk_div_table ast2500_div_table[] = {
+ { 0x0, 4 },
+ { 0x1, 8 },
+ { 0x2, 12 },
+ { 0x3, 16 },
+ { 0x4, 20 },
+ { 0x5, 24 },
+ { 0x6, 28 },
+ { 0x7, 32 },
+ { 0 }
+};
+
+static struct clk_hw *aspeed_ast2400_calc_pll(const char *name, u32 val)
+{
+ unsigned int mult, div;
+
+ if (val & AST2400_HPLL_BYPASS_EN) {
+ /* Pass through mode */
+ mult = div = 1;
+ } else {
+ /* F = 24Mhz * (2-OD) * [(N + 2) / (D + 1)] */
+ u32 n = (val >> 5) & 0x3f;
+ u32 od = (val >> 4) & 0x1;
+ u32 d = val & 0xf;
+
+ mult = (2 - od) * (n + 2);
+ div = d + 1;
+ }
+ return clk_hw_register_fixed_factor(NULL, name, "clkin", 0,
+ mult, div);
+};
+
+static struct clk_hw *aspeed_ast2500_calc_pll(const char *name, u32 val)
+{
+ unsigned int mult, div;
+
+ if (val & AST2500_HPLL_BYPASS_EN) {
+ /* Pass through mode */
+ mult = div = 1;
+ } else {
+ /* F = clkin * [(M+1) / (N+1)] / (P + 1) */
+ u32 p = (val >> 13) & 0x3f;
+ u32 m = (val >> 5) & 0xff;
+ u32 n = val & 0x1f;
+
+ mult = (m + 1) / (n + 1);
+ div = p + 1;
+ }
+
+ return clk_hw_register_fixed_factor(NULL, name, "clkin", 0,
+ mult, div);
+}
+
+static void __init aspeed_ast2400_cc(struct regmap *map)
+{
+ struct clk_hw *hw;
+ u32 val, freq, div;
+
+ /*
+ * CLKIN is the crystal oscillator, 24, 48 or 25MHz selected by
+ * strapping
+ */
+ regmap_read(map, ASPEED_STRAP, &val);
+ if (val & CLKIN_25MHZ_EN)
+ freq = 25000000;
+ else if (val & AST2400_CLK_SOURCE_SEL)
+ freq = 48000000;
+ else
+ freq = 24000000;
+ hw = clk_hw_register_fixed_rate(NULL, "clkin", NULL, 0, freq);
+ pr_debug("clkin @%u MHz\n", freq / 1000000);
+
+ /*
+ * High-speed PLL clock derived from the crystal. This the CPU clock,
+ * and we assume that it is enabled
+ */
+ regmap_read(map, ASPEED_HPLL_PARAM, &val);
+ WARN(val & AST2400_HPLL_STRAPPED, "hpll is strapped not configured");
+ aspeed_clk_data->hws[ASPEED_CLK_HPLL] = aspeed_ast2400_calc_pll("hpll", val);
+
+ /*
+ * Strap bits 11:10 define the CPU/AHB clock frequency ratio (aka HCLK)
+ * 00: Select CPU:AHB = 1:1
+ * 01: Select CPU:AHB = 2:1
+ * 10: Select CPU:AHB = 4:1
+ * 11: Select CPU:AHB = 3:1
+ */
+ regmap_read(map, ASPEED_STRAP, &val);
+ val = (val >> 10) & 0x3;
+ div = val + 1;
+ if (div == 3)
+ div = 4;
+ else if (div == 4)
+ div = 3;
+ hw = clk_hw_register_fixed_factor(NULL, "ahb", "hpll", 0, 1, div);
+ aspeed_clk_data->hws[ASPEED_CLK_AHB] = hw;
+
+ /* APB clock clock selection register SCU08 (aka PCLK) */
+ hw = clk_hw_register_divider_table(NULL, "apb", "hpll", 0,
+ scu_base + ASPEED_CLK_SELECTION, 23, 3, 0,
+ ast2400_div_table,
+ &aspeed_clk_lock);
+ aspeed_clk_data->hws[ASPEED_CLK_APB] = hw;
+}
+
+static void __init aspeed_ast2500_cc(struct regmap *map)
+{
+ struct clk_hw *hw;
+ u32 val, freq, div;
+
+ /* CLKIN is the crystal oscillator, 24 or 25MHz selected by strapping */
+ regmap_read(map, ASPEED_STRAP, &val);
+ if (val & CLKIN_25MHZ_EN)
+ freq = 25000000;
+ else
+ freq = 24000000;
+ hw = clk_hw_register_fixed_rate(NULL, "clkin", NULL, 0, freq);
+ pr_debug("clkin @%u MHz\n", freq / 1000000);
+
+ /*
+ * High-speed PLL clock derived from the crystal. This the CPU clock,
+ * and we assume that it is enabled
+ */
+ regmap_read(map, ASPEED_HPLL_PARAM, &val);
+ aspeed_clk_data->hws[ASPEED_CLK_HPLL] = aspeed_ast2500_calc_pll("hpll", val);
+
+ /* Strap bits 11:9 define the AXI/AHB clock frequency ratio (aka HCLK)*/
+ regmap_read(map, ASPEED_STRAP, &val);
+ val = (val >> 9) & 0x7;
+ WARN(val == 0, "strapping is zero: cannot determine ahb clock");
+ div = 2 * (val + 1);
+ hw = clk_hw_register_fixed_factor(NULL, "ahb", "hpll", 0, 1, div);
+ aspeed_clk_data->hws[ASPEED_CLK_AHB] = hw;
+
+ /* APB clock clock selection register SCU08 (aka PCLK) */
+ regmap_read(map, ASPEED_CLK_SELECTION, &val);
+ val = (val >> 23) & 0x7;
+ div = 4 * (val + 1);
+ hw = clk_hw_register_fixed_factor(NULL, "apb", "hpll", 0, 1, div);
+ aspeed_clk_data->hws[ASPEED_CLK_APB] = hw;
+};
+
static void __init aspeed_cc_init(struct device_node *np)
{
struct regmap *map;
@@ -139,6 +309,13 @@ static void __init aspeed_cc_init(struct device_node *np)
return;
}

+ if (of_device_is_compatible(np, "aspeed,ast2400-scu"))
+ aspeed_ast2400_cc(map);
+ else if (of_device_is_compatible(np, "aspeed,ast2500-scu"))
+ aspeed_ast2500_cc(map);
+ else
+ pr_err("unknown platform, failed to add clocks\n");
+
aspeed_clk_data->num = ASPEED_NUM_CLKS;
ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, aspeed_clk_data);
if (ret)
--
2.14.1
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