[PATCH linux dev-4.17 v2] clk: aspeed: Support HPLL strapping on ast2400

[Joel Stanley]

The HPLL can be configured through a register (SCU24), however some
platforms chose to configure it through the strapping settings and do
not use the register. This was not noticed as the logic for bit 18 in
SCU24 was confused: set means programmed, but the driver read it as set
means strapped.

This gives us the correct HPLL value on Palmetto systems, from which
most of the peripheral clocks are generated.

Signed-off-by: Joel Stanley <joel at jms.id.au>
---
v2: Fix comment and commit message
---
 drivers/clk/clk-aspeed.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
index c17032bc853a..7d8cc412959d 100644
--- a/drivers/clk/clk-aspeed.c
+++ b/drivers/clk/clk-aspeed.c
@@ -24,7 +24,7 @@
 #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_PROGRAMMED BIT(18)
 #define  AST2400_HPLL_BYPASS_EN	BIT(17)
 #define ASPEED_MISC_CTRL	0x2c
 #define  UART_DIV13_EN		BIT(12)
@@ -586,8 +586,24 @@ static void __init aspeed_ast2400_cc(struct regmap *map)
 	 * 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);
+	if (val & AST2400_HPLL_PROGRAMMED) {
+		aspeed_clk_data->hws[ASPEED_CLK_HPLL] =
+			aspeed_ast2400_calc_pll("hpll", val);
+	} else {
+		/* hpll is configured by the strap register */
+		regmap_read(map, ASPEED_STRAP, &val);
+		val = (val >> 8) & 0x3;
+		if (val == 0x00)
+			freq = 384000000;
+		else if (val == 0x01)
+			freq = 360000000;
+		else if (val == 0x02)
+			freq = 336000000;
+		else if (val == 0x03)
+			freq = 408000000;
+		aspeed_clk_data->hws[ASPEED_CLK_HPLL] =
+			clk_hw_register_fixed_rate(NULL, "hpll", "clkin", 0, freq);
+	}
 
 	/*
 	 * Strap bits 11:10 define the CPU/AHB clock frequency ratio (aka HCLK)
-- 
2.17.1