ARM i.MX6: change mxs usbphy clock usage

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

2 files changed, 24 insertions, 4 deletions

diff --git a/Documentation/devicetree/bindings/clock/imx6q-clock.txt b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
index f73fdf595568..969b38e06ad3 100644
--- a/Documentation/devicetree/bindings/clock/imx6q-clock.txt
+++ b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
@@ -203,6 +203,8 @@ clocks and IDs.
         pcie_ref                188
         pcie_ref_125m           189
         enet_ref                190
+        usbphy1_gate            191
+        usbphy2_gate            192
 
 Examples:
 
diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index c0c4e723b7f5..905bec2a08a4 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]);
+        }
+
         /* Set initial power mode */
         imx6q_set_lpm(WAIT_CLOCKED);