ARM: mx25: Add CLKO support

CLKO support is a clock output on mx25 which can output many of the internal
clock sources. It is useful for debugging purpose or also for driving the
audio codec for example.

Signed-off-by: Fabio Estevam <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

Documentation/devicetree/bindings/clock/imx25-clock.txt

···
 	uart5_ipg		124
 	reserved		125
 	wdt_ipg			126
+	cko_div			127
+	cko_sel			128
+	cko			129
 
 Examples:
 

arch/arm/mach-imx/clk-imx25.c

···
 
 static const char *cpu_sel_clks[] = { "mpll", "mpll_cpu_3_4", };
 static const char *per_sel_clks[] = { "ahb", "upll", };
+static const char *cko_sel_clks[] = { "dummy", "osc", "cpu", "ahb",
+				      "ipg", "dummy", "dummy", "dummy",
+				      "dummy", "dummy", "per0", "per2",
+				      "per13", "per14", "usbotg_ahb", "dummy",};
 
 enum mx25_clks {
 	dummy, osc, mpll, upll, mpll_cpu_3_4, cpu_sel, cpu, ahb, usb_div, ipg,
···
 	pwm2_ipg, pwm3_ipg, pwm4_ipg, rngb_ipg, reserved16, scc_ipg, sdma_ipg,
 	sim1_ipg, sim2_ipg, slcdc_ipg, spba_ipg, ssi1_ipg, ssi2_ipg, tsc_ipg,
 	uart1_ipg, uart2_ipg, uart3_ipg, uart4_ipg, uart5_ipg, reserved17,
-	wdt_ipg, clk_max
+	wdt_ipg, cko_div, cko_sel, cko, clk_max
 };
 
 static struct clk *clk[clk_max];
···
 	clk[per13_sel] = imx_clk_mux("per13_sel", ccm(CCM_MCR), 13, 1, per_sel_clks, ARRAY_SIZE(per_sel_clks));
 	clk[per14_sel] = imx_clk_mux("per14_sel", ccm(CCM_MCR), 14, 1, per_sel_clks, ARRAY_SIZE(per_sel_clks));
 	clk[per15_sel] = imx_clk_mux("per15_sel", ccm(CCM_MCR), 15, 1, per_sel_clks, ARRAY_SIZE(per_sel_clks));
+	clk[cko_div] = imx_clk_divider("cko_div", "cko_sel", ccm(CCM_MCR), 24, 6);
+	clk[cko_sel] = imx_clk_mux("cko_sel", ccm(CCM_MCR), 20, 4, cko_sel_clks, ARRAY_SIZE(cko_sel_clks));
+	clk[cko] = imx_clk_gate("cko", "cko_div", ccm(CCM_MCR),  30);
 	clk[per0] = imx_clk_divider("per0", "per0_sel", ccm(CCM_PCDR0), 0, 6);
 	clk[per1] = imx_clk_divider("per1", "per1_sel", ccm(CCM_PCDR0), 8, 6);
 	clk[per2] = imx_clk_divider("per2", "per2_sel", ccm(CCM_PCDR0), 16, 6);
···
 
 	clk_register_clkdev(clk[ipg], "ipg", "imx-gpt.0");
 	clk_register_clkdev(clk[gpt_ipg_per], "per", "imx-gpt.0");
+
+	/*
+	 * Let's initially set up CLKO parent as ipg, since this configuration
+	 * is used on some imx25 board designs to clock the audio codec.
+	 */
+	clk_set_parent(clk[cko_sel], clk[ipg]);
 
 	return 0;
 }