mx5 clocks: Fix get_uart_clk()

This function returned 66500000 instead of the correct lp_apm clock frequency if
the CCM.CSCMR1.uart_clk_sel mux is set to 3.

This patch fixes this issue by introducing the get_standard_pll_sel_clk()
function that will be used by future patches to handle identical muxes used by
many other clocks.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Cc: Stefano Babic <sbabic@denx.de>

arch/arm/cpu/armv7/mx5/clock.c

@@ -331,28 +331,40 @@ static u32 get_ipg_per_clk(void)
 	return freq / ((pred1 + 1) * (pred2 + 1) * (podf + 1));
 }
 
-/*
- * Get the rate of uart clk.
- */
-static u32 get_uart_clk(void)
+/* Get the output clock rate of a standard PLL MUX for peripherals. */
+static u32 get_standard_pll_sel_clk(u32 clk_sel)
 {
-	unsigned int freq, reg, pred, podf;
+	u32 freq;
 
-	reg = readl(&mxc_ccm->cscmr1);
-	switch (MXC_CCM_CSCMR1_UART_CLK_SEL_RD(reg)) {
-	case 0x0:
+	switch (clk_sel & 0x3) {
+	case 0:
 		freq = decode_pll(mxc_plls[PLL1_CLOCK], MXC_HCLK);
 		break;
-	case 0x1:
+	case 1:
 		freq = decode_pll(mxc_plls[PLL2_CLOCK], MXC_HCLK);
 		break;
-	case 0x2:
+	case 2:
 		freq = decode_pll(mxc_plls[PLL3_CLOCK], MXC_HCLK);
 		break;
-	default:
-		return 66500000;
+	case 3:
+		freq = get_lp_apm();
+		break;
 	}
 
+	return freq;
+}
+
+/*
+ * Get the rate of uart clk.
+ */
+static u32 get_uart_clk(void)
+{
+	unsigned int clk_sel, freq, reg, pred, podf;
+
+	reg = readl(&mxc_ccm->cscmr1);
+	clk_sel = MXC_CCM_CSCMR1_UART_CLK_SEL_RD(reg);
+	freq = get_standard_pll_sel_clk(clk_sel);
+
 	reg = readl(&mxc_ccm->cscdr1);
 	pred = MXC_CCM_CSCDR1_UART_CLK_PRED_RD(reg);
 	podf = MXC_CCM_CSCDR1_UART_CLK_PODF_RD(reg);