[PATCH v3 1/3] ARM i.MX6: change mxs usbphy clock usage

[peter.chen@freescale.com (Peter Chen)]

This mxs usbphy is only needs to be on after system boots
up, and software never needs to control it anymore.
Meanwhile, usbphy's parent needs to be notified if usb
is suspend or not. So we design below mxs usbphy usage:

- usbphy1_gate and usbphy2_gate:
Their parents are dummy clock, we only needs to enable
it after system boots up.
- usbphy1 and usbphy2
Usage reserved bit for this clock, in that case, the refcount
will be updated, but without hardware changing.

Signed-off-by: Peter Chen <peter.chen@freescale.com>
---
Changes for v3:
- Add new clk for usbphy clk gate which is only used 
at system boots up process.

Changes for v2:
- Use reserved bit for usb phy clk control

 arch/arm/mach-imx/clk-imx6q.c |   26 ++++++++++++++++++++++----
 1 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index 7f2c10c..ccb24cf 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -154,8 +154,8 @@ enum mx6q_clks {
 	usdhc4, vdo_axi, vpu_axi, cko1, pll1_sys, pll2_bus, pll3_usb_otg,
 	pll4_audio, pll5_video, pll8_mlb, pll7_usb_host, pll6_enet, ssi1_ipg,
 	ssi2_ipg, ssi3_ipg, rom, usbphy1, usbphy2, ldb_di0_div_3_5, ldb_di1_div_3_5,
-	sata_ref, sata_ref_100m, pcie_ref, pcie_ref_125m, enet_ref,
-	clk_max
+	sata_ref, sata_ref_100m, pcie_ref, pcie_ref_125m, enet_ref, usbphy1_gate,
+	usbphy2_gate, clk_max
 };
 
 static struct clk *clk[clk_max];
@@ -208,8 +208,21 @@ int __init mx6q_clocks_init(void)
 	clk[pll7_usb_host] = imx_clk_pllv3(IMX_PLLV3_USB,	"pll7_usb_host","osc", base + 0x20, 0x3);
 	clk[pll8_mlb]      = imx_clk_pllv3(IMX_PLLV3_MLB,	"pll8_mlb",	"osc", base + 0xd0, 0x0);
 
-	clk[usbphy1] = imx_clk_gate("usbphy1", "pll3_usb_otg", base + 0x10, 6);
-	clk[usbphy2] = imx_clk_gate("usbphy2", "pll7_usb_host", base + 0x20, 6);
+	/*
+	 * Bit 20 is the reserved and read-only bit, we do this only for:
+	 * - Do nothing for usbphy clk_enable/disable
+	 * - Keep refcount when do usbphy clk_enable/disable, in that case,
+	 * the clk framework may need to enable/disable usbphy's parent
+	 */
+	clk[usbphy1] = imx_clk_gate("usbphy1", "pll3_usb_otg", base + 0x10, 20);
+	clk[usbphy2] = imx_clk_gate("usbphy2", "pll7_usb_host", base + 0x20, 20);
+
+	/*
+	 * usbphy*_gate needs to be on after system boots up, and software
+	 * never needs to control it anymore.
+	 */
+	clk[usbphy1_gate] = imx_clk_gate("usbphy1_gate", "dummy", base + 0x10, 6);
+	clk[usbphy2_gate] = imx_clk_gate("usbphy2_gate", "dummy", base + 0x20, 6);
 
 	clk[sata_ref] = imx_clk_fixed_factor("sata_ref", "pll6_enet", 1, 5);
 	clk[pcie_ref] = imx_clk_fixed_factor("pcie_ref", "pll6_enet", 1, 4);
@@ -436,6 +449,11 @@ int __init mx6q_clocks_init(void)
 	for (i = 0; i < ARRAY_SIZE(clks_init_on); i++)
 		clk_prepare_enable(clk[clks_init_on[i]]);
 
+	if (IS_ENABLED(CONFIG_USB_MXS_PHY)) {
+		clk_prepare_enable(clk[usbphy1_gate]);
+		clk_prepare_enable(clk[usbphy2_gate]);
+	}
+
 	np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-gpt");
 	base = of_iomap(np, 0);
 	WARN_ON(!base);
-- 
1.7.0.4