exynos5420: add a peripheral clock select --> PLL decoder

This adds a helper function to translate between peripheral clock
select fields in clock source registers and PLLs. Some of this was
already done to handle a few special cases, this generalizes the
earlier work so that follow-up patches can do further clean-up.

Unfortunately, the PLLs represented by clock select fields in
various modules are not uniformly ordered. So for now we focus on
peripheral clock sources only.

Signed-off-by: David Hendricks <dhendrix@chromium.org>

Change-Id: Id58a3e488650d09e6a35c22d5394fcbf0ee9ddff
Reviewed-on: https://gerrit.chromium.org/gerrit/65283
Commit-Queue: David Hendricks <dhendrix@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/4462
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/cpu/samsung/exynos5420/clk.h

@@ -25,6 +25,7 @@
 
 enum periph_id;
 
+/* This master list of PLLs is ordered arbitrarily. */
 #define APLL	0
 #define MPLL	1
 #define EPLL	2
@@ -35,16 +36,7 @@ enum periph_id;
 #define SPLL	7
 #define CPLL	8
 #define DPLL	9
-
+#define IPLL	10
-enum pll_src_bit {
-	EXYNOS_SRC_CPLL = 1,
-	EXYNOS_SRC_DPLL = 2,
-	EXYNOS_SRC_MPLL = 3,
-	EXYNOS_SRC_SPLL = 4,
-	EXYNOS_SRC_IPLL = 5,
-	EXYNOS_SRC_EPLL = 6,
-	EXYNOS_SRC_RPLL = 7,
-};
 
 /* *
  * This structure is to store the src bit, div bit and prediv bit

src/cpu/samsung/exynos5420/clock.c

@@ -151,6 +151,50 @@ unsigned long get_pll_clk(int pllreg)
 	return fout;
 }
 
+enum peripheral_clock_select {
+	PERIPH_SRC_CPLL = 1,
+	PERIPH_SRC_DPLL = 2,
+	PERIPH_SRC_MPLL = 3,
+	PERIPH_SRC_SPLL = 4,
+	PERIPH_SRC_IPLL = 5,
+	PERIPH_SRC_EPLL = 6,
+	PERIPH_SRC_RPLL = 7,
+};
+
+static int clock_select_to_pll(enum peripheral_clock_select sel)
+{
+	int pll;
+
+	switch (sel) {
+	case PERIPH_SRC_CPLL:
+		pll = CPLL;
+		break;
+	case PERIPH_SRC_DPLL:
+		pll = DPLL;
+		break;
+	case PERIPH_SRC_MPLL:
+		pll = MPLL;
+		break;
+	case PERIPH_SRC_SPLL:
+		pll = SPLL;
+		break;
+	case PERIPH_SRC_IPLL:
+		pll = IPLL;
+		break;
+	case PERIPH_SRC_EPLL:
+		pll = EPLL;
+		break;
+	case PERIPH_SRC_RPLL:
+		pll = RPLL;
+		break;
+	default:
+		pll = -1;
+		break;
+	}
+
+	return pll;
+}
+
 unsigned long clock_get_periph_rate(enum periph_id peripheral)
 {
 	struct clk_bit_info *bit_info = &clk_bit_info[peripheral];
@@ -206,17 +250,14 @@ unsigned long clock_get_periph_rate(enum periph_id peripheral)
 
 	src = (src >> bit_info->src_bit) & 0xf;
 
-	switch (src) {
+	src = clock_select_to_pll(src);
-	case EXYNOS_SRC_MPLL:
+	if (src < 0) {
-		sclk = get_pll_clk(MPLL);
+		printk(BIOS_DEBUG, "%s: cannot determine source PLL", __func__);
-		break;
+		return -1;
-	case EXYNOS_SRC_EPLL:
-		sclk = get_pll_clk(EPLL);
-		break;
-	default:
-		return 0;
 	}
 
+	sclk = get_pll_clk(src);
+
 	/* Ratio clock division for this peripheral */
 	sub_div = (div >> bit_info->div_bit) & 0xf;
 	sub_clk = sclk / (sub_div + 1);