ARM: i.MX: Reset OTG controller during startup

When booting from USB it's sometimes observed that the USB stack on
the remote host gets confused. This happens when we adjust the PLLs
the USB controller is hanging on. The ROM just leaves the USB controller
enabled when it passes control to the bootloader, so in case the usb
clks are enabled make sure we reset the otg  before doing any critical
clock operations.

This is currently done for i.MX50, i.MX51, i.MX53 and i.MX6, but a
similar thing can happen on other i.MXes aswell.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

5 files changed, 40 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/imx50.c b/arch/arm/mach-imx/imx50.c
index f7cbc9d4ba..4fd5481670 100644
--- a/arch/arm/mach-imx/imx50.c
+++ b/arch/arm/mach-imx/imx50.c
@@ -22,6 +22,7 @@
 #include <mach/clock-imx51_53.h>
 #include <mach/generic.h>
 #include <mach/reset-reason.h>
+#include <mach/usb.h>
 
 #define SI_REV 0x48
 
@@ -90,6 +91,9 @@ void imx50_init_lowlevel_early(unsigned int cpufreq_mhz)
 	void __iomem *ccm = IOMEM(MX50_CCM_BASE_ADDR);
 	u32 r;
 
+	if ((readl(ccm + MX5_CCM_CCGR2) & MX5_CCM_CCGRx_CG13_MASK))
+		imx_reset_otg_controller(IOMEM(MX50_OTG_BASE_ADDR));
+
 	imx5_init_lowlevel();
 
 	/*
diff --git a/arch/arm/mach-imx/imx51.c b/arch/arm/mach-imx/imx51.c
index ec8cdd868b..7404254bee 100644
--- a/arch/arm/mach-imx/imx51.c
+++ b/arch/arm/mach-imx/imx51.c
@@ -22,6 +22,7 @@
 #include <mach/clock-imx51_53.h>
 #include <mach/generic.h>
 #include <mach/reset-reason.h>
+#include <mach/usb.h>
 
 #define IIM_SREV 0x24
 
@@ -140,6 +141,9 @@ void imx51_init_lowlevel(unsigned int cpufreq_mhz)
 	u32 r;
 	int rev = imx51_silicon_revision();
 
+	if ((readl(ccm + MX5_CCM_CCGR2) & MX5_CCM_CCGRx_CG13_MASK))
+		imx_reset_otg_controller(IOMEM(MX51_OTG_BASE_ADDR));
+
 	imx5_init_lowlevel();
 
 	/* disable write combine for TO 2 and lower revs */
diff --git a/arch/arm/mach-imx/imx53.c b/arch/arm/mach-imx/imx53.c
index b22929f749..f8e34a39da 100644
--- a/arch/arm/mach-imx/imx53.c
+++ b/arch/arm/mach-imx/imx53.c
@@ -22,6 +22,7 @@
 #include <mach/clock-imx51_53.h>
 #include <mach/generic.h>
 #include <mach/reset-reason.h>
+#include <mach/usb.h>
 
 #define SI_REV 0x48
 
@@ -88,6 +89,9 @@ void imx53_init_lowlevel_early(unsigned int cpufreq_mhz)
 	void __iomem *ccm = (void __iomem *)MX53_CCM_BASE_ADDR;
 	u32 r, cbcdr, cbcmr;
 
+	if ((readl(ccm + MX5_CCM_CCGR2) & MX5_CCM_CCGRx_CG13_MASK))
+		imx_reset_otg_controller(IOMEM(MX53_OTG_BASE_ADDR));
+
 	imx5_init_lowlevel();
 
 	/*
diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
index 3d95c9e374..cc368c5820 100644
--- a/arch/arm/mach-imx/imx6.c
+++ b/arch/arm/mach-imx/imx6.c
@@ -24,11 +24,13 @@
 #include <mach/imx6-anadig.h>
 #include <mach/imx6-regs.h>
 #include <mach/generic.h>
+#include <mach/usb.h>
 #include <asm/mmu.h>
 #include <asm/cache-l2x0.h>
 
 #include <poweroff.h>
 #include <mach/imx6-regs.h>
+#include <mach/clock-imx6.h>
 #include <io.h>
 
 #define CLPCR				0x54
@@ -52,6 +54,9 @@ static void imx6_init_lowlevel(void)
 	uint32_t periph_sel_2;
 	uint32_t reg;
 
+	if ((readl(MXC_CCM_CCGR6) & 0x3))
+		imx_reset_otg_controller(IOMEM(MX6_OTG_BASE_ADDR));
+
 	/*
 	 * Set all MPROTx to be non-bufferable, trusted for R/W,
 	 * not forced to user-mode.
diff --git a/arch/arm/mach-imx/include/mach/usb.h b/arch/arm/mach-imx/include/mach/usb.h
index 85528d77e6..3b5e24d1cc 100644
--- a/arch/arm/mach-imx/include/mach/usb.h
+++ b/arch/arm/mach-imx/include/mach/usb.h
@@ -14,4 +14,27 @@
 int imx6_usb_phy2_disable_oc(void);
 int imx6_usb_phy2_enable(void);
 
+#define USBCMD	0x140
+#define USB_CMD_RESET	0x00000002
+
+/*
+ * imx_reset_otg_controller - reset the USB OTG controller
+ * @base: The base address of the controller
+ *
+ * When booting from USB the ROM just leaves the controller enabled. This can
+ * have bad side effects when for example we change PLL frequencies. In this
+ * case it is seen that the hub the board is connected to gets confused and USB
+ * is no longer working properly on the remote host. This function resets the
+ * OTG controller. It should be called before the clocks the controller hangs on
+ * is fiddled with.
+ */
+static inline void imx_reset_otg_controller(void __iomem *base)
+{
+	u32 r;
+
+	r = readl(base + USBCMD);
+	r |= USB_CMD_RESET;
+	writel(r, base + USBCMD);
+}
+
 #endif /* __MACH_USB_H_*/