sunxi: sun9i: make more clock functions SPL only

In clock_sun9i.c, responsible for (mostly early) clock setup on the
Allwinner A80 SoC, many functions are only needed by the SPL, and are
thus already guarded by CONFIG_SPL_BUILD.

Over the years drivers like for the UART or I2C were converted to DM, and
they care about clock setup themselves now, by using a proper DM clock
driver.

This means those devices need the clock setup functions here for the SPL
only. Move some functions around, to group all SPL-only function within
one #ifdef guard. Some functions were exported, but never used outside
of this file, so remove their prototypes from the header file and mark
them as static.

This avoids unnecessary code in U-Boot proper and helps further
refactoring. Add some comments on the way to help understanding of the
file.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/arch/arm/mach-sunxi/clock_sun9i.c b/arch/arm/mach-sunxi/clock_sun9i.c
index edaff9a..5913e40 100644
--- a/arch/arm/mach-sunxi/clock_sun9i.c
+++ b/arch/arm/mach-sunxi/clock_sun9i.c
@@ -17,6 +17,52 @@
 
 #ifdef CONFIG_SPL_BUILD
 
+static void clock_set_pll2(unsigned int clk)
+{
+	struct sunxi_ccm_reg * const ccm =
+		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
+	const int p = 0;
+
+	/* Switch cluster 1 to 24MHz clock while changing PLL2 */
+	clrsetbits_le32(&ccm->cpu_clk_source, C1_CPUX_CLK_SRC_MASK,
+			C1_CPUX_CLK_SRC_OSC24M);
+
+	writel(CCM_PLL2_CTRL_EN | CCM_PLL2_CTRL_P(p) |
+	       CCM_PLL2_CLOCK_TIME_2 | CCM_PLL2_CTRL_N(clk / 24000000),
+	       &ccm->pll2_c1_cfg);
+
+	sdelay(2000);
+
+	/* Switch cluster 1 back to PLL2 */
+	clrsetbits_le32(&ccm->cpu_clk_source, C1_CPUX_CLK_SRC_MASK,
+			C1_CPUX_CLK_SRC_PLL2);
+}
+
+static void clock_set_pll4(unsigned int clk)
+{
+	struct sunxi_ccm_reg * const ccm =
+		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
+
+	writel(CCM_PLL4_CTRL_EN | CCM_PLL4_CTRL_N(clk / 24000000),
+	       &ccm->pll4_periph0_cfg);
+
+	sdelay(2000);
+}
+
+static void clock_set_pll12(unsigned int clk)
+{
+	struct sunxi_ccm_reg * const ccm =
+		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
+
+	if (readl(&ccm->pll12_periph1_cfg) & CCM_PLL12_CTRL_EN)
+		return;
+
+	writel(CCM_PLL12_CTRL_EN | CCM_PLL12_CTRL_N(clk / 24000000),
+	       &ccm->pll12_periph1_cfg);
+
+	sdelay(2000);
+}
+
 void clock_init_safe(void)
 {
 	struct sunxi_ccm_reg * const ccm =
@@ -63,7 +109,6 @@
 	/* set enable-bit in TSTAMP_CTRL_REG */
 	writel(1, 0x01720000);
 }
-#endif
 
 void clock_init_uart(void)
 {
@@ -80,7 +125,6 @@
 			   CONFIG_CONS_INDEX - 1));
 }
 
-#ifdef CONFIG_SPL_BUILD
 void clock_set_pll1(unsigned int clk)
 {
 	struct sunxi_ccm_reg * const ccm =
@@ -108,27 +152,6 @@
 			C0_CPUX_CLK_SRC_PLL1);
 }
 
-void clock_set_pll2(unsigned int clk)
-{
-	struct sunxi_ccm_reg * const ccm =
-		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
-	const int p = 0;
-
-	/* Switch cluster 1 to 24MHz clock while changing PLL2 */
-	clrsetbits_le32(&ccm->cpu_clk_source, C1_CPUX_CLK_SRC_MASK,
-			C1_CPUX_CLK_SRC_OSC24M);
-
-	writel(CCM_PLL2_CTRL_EN | CCM_PLL2_CTRL_P(p) |
-	       CCM_PLL2_CLOCK_TIME_2 | CCM_PLL2_CTRL_N(clk / 24000000),
-	       &ccm->pll2_c1_cfg);
-
-	sdelay(2000);
-
-	/* Switch cluster 1 back to PLL2 */
-	clrsetbits_le32(&ccm->cpu_clk_source, C1_CPUX_CLK_SRC_MASK,
-			C1_CPUX_CLK_SRC_PLL2);
-}
-
 void clock_set_pll6(unsigned int clk)
 {
 	struct sunxi_ccm_reg * const ccm =
@@ -143,32 +166,6 @@
 	sdelay(2000);
 }
 
-void clock_set_pll12(unsigned int clk)
-{
-	struct sunxi_ccm_reg * const ccm =
-		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
-
-	if (readl(&ccm->pll12_periph1_cfg) & CCM_PLL12_CTRL_EN)
-		return;
-
-	writel(CCM_PLL12_CTRL_EN | CCM_PLL12_CTRL_N(clk / 24000000),
-	       &ccm->pll12_periph1_cfg);
-
-	sdelay(2000);
-}
-
-
-void clock_set_pll4(unsigned int clk)
-{
-	struct sunxi_ccm_reg * const ccm =
-		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
-
-	writel(CCM_PLL4_CTRL_EN | CCM_PLL4_CTRL_N(clk / 24000000),
-	       &ccm->pll4_periph0_cfg);
-
-	sdelay(2000);
-}
-#endif
 
 int clock_twi_onoff(int port, int state)
 {
@@ -193,7 +190,9 @@
 
 	return 0;
 }
+#endif /* CONFIG_SPL_BUILD */
 
+/* PLL_PERIPH0 clock (used by the MMC driver) */
 unsigned int clock_get_pll4_periph0(void)
 {
 	struct sunxi_ccm_reg *const ccm =