mx25: Add function to set PER clocks

Introduce the imx_set_perclk() function to make it possible to set the
PER clocks.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

arch/arm/cpu/arm926ejs/mx25/generic.c

@@ -113,6 +113,25 @@ static ulong imx_get_perclk(int clk)
 	return fref / div;
 }
 
+int imx_set_perclk(enum mxc_clock clk, bool from_upll, unsigned int freq)
+{
+	struct ccm_regs *ccm = (struct ccm_regs *)IMX_CCM_BASE;
+	ulong fref = from_upll ? imx_get_upllclk() : imx_get_ahbclk();
+	ulong div = (fref + freq - 1) / freq;
+
+	if (clk > MXC_UART_CLK || !div || --div > CCM_PERCLK_MASK)
+		return -EINVAL;
+
+	clrsetbits_le32(&ccm->pcdr[CCM_PERCLK_REG(clk)],
+			CCM_PERCLK_MASK << CCM_PERCLK_SHIFT(clk),
+			div << CCM_PERCLK_SHIFT(clk));
+	if (from_upll)
+		setbits_le32(&ccm->mcr, 1 << clk);
+	else
+		clrbits_le32(&ccm->mcr, 1 << clk);
+	return 0;
+}
+
 unsigned int mxc_get_clock(enum mxc_clock clk)
 {
 	if (clk >= MXC_CLK_NUM)

arch/arm/include/asm/arch-mx25/clock.h

@@ -51,6 +51,7 @@ enum mxc_clock {
 	MXC_CLK_NUM
 };
 
+int imx_set_perclk(enum mxc_clock clk, bool from_upll, unsigned int freq);
 unsigned int mxc_get_clock(enum mxc_clock clk);
 
 #define imx_get_uartclk()	mxc_get_clock(MXC_UART_CLK)