ARM: imx6q: support ptp and rmii clock from pad

On imx6qdl, the ENET RMII and PTP clock can come from either internal
ANATOP/CCM or external clock source through pad GPIO_16.  But in case
of the external clock source, bit IOMUXC_GPR1[21] needs to be cleared.

The patch adds the support for systems that use an external clock source
and distinguishes above two cases by checking if the PTP clock specified
in device tree is the one coming from the internal ANATOP/CCM.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/clk-imx6q.c

@@ -437,6 +437,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 
 	clk_register_clkdev(clk[gpt_ipg], "ipg", "imx-gpt.0");
 	clk_register_clkdev(clk[gpt_ipg_per], "per", "imx-gpt.0");
+	clk_register_clkdev(clk[enet_ref], "enet_ref", NULL);
 
 	if ((imx_get_soc_revision() != IMX_CHIP_REVISION_1_0) ||
 	    cpu_is_imx6dl()) {

arch/arm/mach-imx/mach-imx6q.c

@@ -182,16 +182,50 @@ static void __init imx6q_enet_phy_init(void)
 
 static void __init imx6q_1588_init(void)
 {
+	struct device_node *np;
+	struct clk *ptp_clk;
+	struct clk *enet_ref;
 	struct regmap *gpr;
+	u32 clksel;
 
+	np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-fec");
+	if (!np) {
+		pr_warn("%s: failed to find fec node\n", __func__);
+		return;
+	}
+
+	ptp_clk = of_clk_get(np, 2);
+	if (IS_ERR(ptp_clk)) {
+		pr_warn("%s: failed to get ptp clock\n", __func__);
+		goto put_node;
+	}
+
+	enet_ref = clk_get_sys(NULL, "enet_ref");
+	if (IS_ERR(enet_ref)) {
+		pr_warn("%s: failed to get enet clock\n", __func__);
+		goto put_ptp_clk;
+	}
+
+	/*
+	 * If enet_ref from ANATOP/CCM is the PTP clock source, we need to
+	 * set bit IOMUXC_GPR1[21].  Or the PTP clock must be from pad
+	 * (external OSC), and we need to clear the bit.
+	 */
+	clksel = ptp_clk == enet_ref ? IMX6Q_GPR1_ENET_CLK_SEL_ANATOP :
+				       IMX6Q_GPR1_ENET_CLK_SEL_PAD;
 	gpr = syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
 	if (!IS_ERR(gpr))
 		regmap_update_bits(gpr, IOMUXC_GPR1,
 				IMX6Q_GPR1_ENET_CLK_SEL_MASK,
-				IMX6Q_GPR1_ENET_CLK_SEL_ANATOP);
+				clksel);
 	else
 		pr_err("failed to find fsl,imx6q-iomux-gpr regmap\n");
 
+	clk_put(enet_ref);
+put_ptp_clk:
+	clk_put(ptp_clk);
+put_node:
+	of_node_put(np);
 }
 
 static void __init imx6q_init_machine(void)