ARM: omap3: Implement dpll5 (HSUSB clk) workaround for OMAP36xx/AM/DM37xx according to errata sprz318e.

In chapter 'Advisory 2.1 USB Host Clock Drift Causes USB Spec Non-compliance in Certain Configurations' of the TI Errata it is recommended to use certain div/mult values for the DPLL5 clock setup.
So far u-boot used the old 34xx values, so I added the errata recommended values specificly for 36xx init only.
Also, the FSEL registers exist no longer, so removed them from init.

Tested this on a AM3703 board with 19.2MHz oscillator, which previously couldnt lock the dpll5 (kernel complained). As a consequence the EHCI USB port wasnt usable in U-Boot and kernel. With this patch, kernel panics disappear and USB working fine in u-boot and kernel.

Signed-off-by: Andreas Naumann <anaumann@ultratronik.de>
[trini: Add extern to <asm/arch-omap3/clock.h>
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/arch/arm/cpu/armv7/omap3/clock.c b/arch/arm/cpu/armv7/omap3/clock.c
index 3acbc9c..e903ed9 100644
--- a/arch/arm/cpu/armv7/omap3/clock.c
+++ b/arch/arm/cpu/armv7/omap3/clock.c
@@ -478,6 +478,24 @@
 	wait_on_value(ST_PERIPH_CLK, 2, &prcm_base->idlest_ckgen, LDELAY);
 }
 
+static void dpll5_init_36xx(u32 sil_index, u32 clk_index)
+{
+	struct prcm *prcm_base = (struct prcm *)PRCM_BASE;
+	dpll_param *ptr = (dpll_param *) get_36x_per2_dpll_param();
+
+	/* Moving it to the right sysclk base */
+	ptr = ptr + clk_index;
+
+	/* PER2 DPLL (DPLL5) */
+	sr32(&prcm_base->clken2_pll, 0, 3, PLL_STOP);
+	wait_on_value(1, 0, &prcm_base->idlest2_ckgen, LDELAY);
+	sr32(&prcm_base->clksel5_pll, 0, 5, ptr->m2); /* set M2 (usbtll_fck) */
+	sr32(&prcm_base->clksel4_pll, 8, 11, ptr->m); /* set m (11-bit multiplier) */
+	sr32(&prcm_base->clksel4_pll, 0, 7, ptr->n); /* set n (7-bit divider)*/
+	sr32(&prcm_base->clken2_pll, 0, 3, PLL_LOCK);   /* lock mode */
+	wait_on_value(1, 1, &prcm_base->idlest2_ckgen, LDELAY);
+}
+
 static void mpu_init_36xx(u32 sil_index, u32 clk_index)
 {
 	struct prcm *prcm_base = (struct prcm *)PRCM_BASE;
@@ -582,7 +600,7 @@
 
 		dpll3_init_36xx(0, clk_index);
 		dpll4_init_36xx(0, clk_index);
-		dpll5_init_34xx(0, clk_index);
+		dpll5_init_36xx(0, clk_index);
 		iva_init_36xx(0, clk_index);
 		mpu_init_36xx(0, clk_index);