SPEAr: explicitly select clk src for UART

UART in u-boot intends to run on 48MHz clock supplied by USB PLL.
Explicitly select the intended clock source.

Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
Signed-off-by: Amit Virdi <amit.virdi@st.com>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>

arch/arm/cpu/arm926ejs/spear/cpu.c

@@ -30,7 +30,7 @@ int arch_cpu_init(void)
 {
 	struct misc_regs *const misc_p =
 	    (struct misc_regs *)CONFIG_SPEAR_MISCBASE;
-	u32 periph1_clken;
+	u32 periph1_clken, periph_clk_cfg;
 
 	periph1_clken = readl(&misc_p->periph1_clken);
 
@@ -42,6 +42,11 @@ int arch_cpu_init(void)
 
 #if defined(CONFIG_PL011_SERIAL)
 	periph1_clken |= MISC_UART0ENB;
+
+	periph_clk_cfg = readl(&misc_p->periph_clk_cfg);
+	periph_clk_cfg &= ~CONFIG_SPEAR_UARTCLKMSK;
+	periph_clk_cfg |= CONFIG_SPEAR_UART48M;
+	writel(periph_clk_cfg, &misc_p->periph_clk_cfg);
 #endif
 #if defined(CONFIG_DESIGNWARE_ETH)
 	periph1_clken |= MISC_ETHENB;

arch/arm/include/asm/arch-spear/spr_misc.h

@@ -110,6 +110,8 @@ struct misc_regs {
 /* PERIPH_CLK_CFG value */
 #define MISC_GPT3SYNTH			0x00000400
 #define MISC_GPT4SYNTH			0x00000800
+#define CONFIG_SPEAR_UART48M		0
+#define CONFIG_SPEAR_UARTCLKMSK		(0x1 << 4)
 
 /* PRSC_CLK_CFG value */
 /*