ARM: OMAP: Fix reprogramming of dpll1 rate

Commit a66cb345 (ARM: OMAP: Map SRAM
later on with ioremap_exec()) moved the SRAM init to happen later
to remove a dependency to early SoC detection for map_io.

This broke booting on some boards not using Kconfig option for
OMAP_CLOCKS_SET_BY_BOOTLOADER as the dpll1 reprogramming would
cause the following error:

kernel BUG at arch/arm/plat-omap/sram.c:226!
Internal error: Oops - undefined instruction: 0 [#1] PREEMPT
Modules linked in:

CPU: 0    Not tainted  (3.2.0-rc1-e3 #9)
PC is at omap_sram_reprogram_clock+0x28/0x30
LR is at omap1_select_table_rate+0x88/0xb4
pc : [<c001b0c4>]    lr : [<c0019f54>]    psr: 600000d3
sp : c035bf10  ip : c035bf20  fp : c035bf1c
r10: c035bfd4  r9 : 54029252  r8 : c03f8120
r7 : c0362b50  r6 : 00b71b00  r5 : c03873cc  r4 : c0362b40
r3 : 00000000  r2 : c0362b40  r1 : 0000010a  r0 : 00002cb0
Flags: nZCv  IRQs off  FIQs off  Mode SVC_32  ISA ARM  Segment kernel
Control: 0000317f  Table: 10004000  DAC: 00000017
Process swapper (pid: 0, stack limit = 0xc035a270)
Stack: (0xc035bf10 to 0xc035c000)
bf00:                                     c035bf3c c035bf20 c0019f54 c001b0ac
bf20: 00001000 00002cb3 00000004 c035ed4c c035bf74 c035bf40 c033ea24 c0019edc
bf40: c02f526c 00000002 00000015 bc058c9b 93111a16 c035335c 02000000 c035ed4c
bf60: c035ed4c c03f8120 c035bf84 c035bf78 c00194c4 c033e8ec c035bfc4 c035bf88
bf80: c033bc24 c00194a0 c035bf90 c035bf98 00000000 00000000 00000000 00000000
bfa0: 00000001 00000000 c0354678 c035ece4 10004000 103532f4 c035bff4 c035bfc8
bfc0: c0338574 c033b598 00000000 00000000 00000000 c035467c 0000317d c035c03c
bfe0: c0354678 c035ece4 00000000 c035bff8 10008040 c0338508 00000000 00000000
Backtrace:
[<c001b09c>] (omap_sram_reprogram_clock+0x0/0x30) from [<c0019f54>] (omap1_select_table_rate+0x88/0xb4)
[<c0019ecc>] (omap1_select_table_rate+0x0/0xb4) from [<c033ea24>] (omap1_clk_init+0x148/0x334)
 r7:c035ed4c r6:00000004 r5:00002cb3 r4:00001000
[<c033e8dc>] (omap1_clk_init+0x0/0x334) from [<c00194c4>] (omap1_init_early+0x34/0x48)
 r8:c03f8120 r7:c035ed4c r6:c035ed4c r5:02000000 r4:c035335c
[<c0019490>] (omap1_init_early+0x0/0x48) from [<c033bc24>] (setup_arch+0x69c/0x79c)
[<c033b588>] (setup_arch+0x0/0x79c) from [<c0338574>] (start_kernel+0x7c/0x2f4)
[<c03384f8>] (start_kernel+0x0/0x2f4) from [<10008040>] (0x10008040)
 r7:c035ece4 r6:c0354678 r5:c035c03c r4:0000317d
Code: 0a000002 e1a0e00f e12fff13 e89da800 (e7f001f2)

Fix this by adding omap1_clk_late_init() that only reprograms dpll1
if the bootloader rate is less than 60MHz. This also allows removing
of the OMAP_CLOCKS_SET_BY_BOOTLOADER option.
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/configs/omap1_defconfig

@@ -48,7 +48,6 @@ CONFIG_MACH_SX1=y
 CONFIG_MACH_NOKIA770=y
 CONFIG_MACH_AMS_DELTA=y
 CONFIG_MACH_OMAP_GENERIC=y
-CONFIG_OMAP_CLOCKS_SET_BY_BOOTLOADER=y
 CONFIG_OMAP_ARM_216MHZ=y
 CONFIG_OMAP_ARM_195MHZ=y
 CONFIG_OMAP_ARM_192MHZ=y

arch/arm/mach-omap1/Kconfig

@@ -171,14 +171,6 @@ config MACH_OMAP_GENERIC
 comment "OMAP CPU Speed"
 	depends on ARCH_OMAP1
 
-config OMAP_CLOCKS_SET_BY_BOOTLOADER
-	bool "OMAP clocks set by bootloader"
-	depends on ARCH_OMAP1
-	help
-	  Enable this option to prevent the kernel from overriding the clock
-	  frequencies programmed by bootloader for MPU, DSP, MMUs, TC,
-	  internal LCD controller and MPU peripherals.
-
 config OMAP_ARM_216MHZ
 	bool "OMAP ARM 216 MHz CPU (1710 only)"
         depends on ARCH_OMAP1 && ARCH_OMAP16XX

arch/arm/mach-omap1/clock.h

@@ -17,7 +17,8 @@
 
 #include <plat/clock.h>
 
-extern int __init omap1_clk_init(void);
+int omap1_clk_init(void);
+void omap1_clk_late_init(void);
 extern int omap1_clk_enable(struct clk *clk);
 extern void omap1_clk_disable(struct clk *clk);
 extern long omap1_clk_round_rate(struct clk *clk, unsigned long rate);

arch/arm/mach-omap1/clock_data.c

@@ -767,6 +767,15 @@ static struct clk_functions omap1_clk_functions = {
 	.clk_disable_unused	= omap1_clk_disable_unused,
 };
 
+static void __init omap1_show_rates(void)
+{
+	pr_notice("Clocking rate (xtal/DPLL1/MPU): "
+			"%ld.%01ld/%ld.%01ld/%ld.%01ld MHz\n",
+		ck_ref.rate / 1000000, (ck_ref.rate / 100000) % 10,
+		ck_dpll1.rate / 1000000, (ck_dpll1.rate / 100000) % 10,
+		arm_ck.rate / 1000000, (arm_ck.rate / 100000) % 10);
+}
+
 int __init omap1_clk_init(void)
 {
 	struct omap_clk *c;
@@ -835,9 +844,12 @@ int __init omap1_clk_init(void)
 	/* We want to be in syncronous scalable mode */
 	omap_writew(0x1000, ARM_SYSST);
 
-#ifdef CONFIG_OMAP_CLOCKS_SET_BY_BOOTLOADER
-	/* Use values set by bootloader. Determine PLL rate and recalculate
-	 * dependent clocks as if kernel had changed PLL or divisors.
+
+	/*
+	 * Initially use the values set by bootloader. Determine PLL rate and
+	 * recalculate dependent clocks as if kernel had changed PLL or
+	 * divisors. See also omap1_clk_late_init() that can reprogram dpll1
+	 * after the SRAM is initialized.
 	 */
 	{
 		unsigned pll_ctl_val = omap_readw(DPLL_CTL);
@@ -862,25 +874,10 @@ int __init omap1_clk_init(void)
 			}
 		}
 	}
-#else
-	/* Find the highest supported frequency and enable it */
-	if (omap1_select_table_rate(&virtual_ck_mpu, ~0)) {
-		printk(KERN_ERR "System frequencies not set. Check your config.\n");
-		/* Guess sane values (60MHz) */
-		omap_writew(0x2290, DPLL_CTL);
-		omap_writew(cpu_is_omap7xx() ? 0x3005 : 0x1005, ARM_CKCTL);
-		ck_dpll1.rate = 60000000;
-	}
-#endif
 	propagate_rate(&ck_dpll1);
 	/* Cache rates for clocks connected to ck_ref (not dpll1) */
 	propagate_rate(&ck_ref);
-	printk(KERN_INFO "Clocking rate (xtal/DPLL1/MPU): "
-		"%ld.%01ld/%ld.%01ld/%ld.%01ld MHz\n",
-	       ck_ref.rate / 1000000, (ck_ref.rate / 100000) % 10,
-	       ck_dpll1.rate / 1000000, (ck_dpll1.rate / 100000) % 10,
-	       arm_ck.rate / 1000000, (arm_ck.rate / 100000) % 10);
-
+	omap1_show_rates();
 	if (machine_is_omap_perseus2() || machine_is_omap_fsample()) {
 		/* Select slicer output as OMAP input clock */
 		omap_writew(omap_readw(OMAP7XX_PCC_UPLD_CTRL) & ~0x1,
@@ -925,3 +922,21 @@ int __init omap1_clk_init(void)
 
 	return 0;
 }
+
+#define OMAP1_DPLL1_SANE_VALUE	60000000
+
+void __init omap1_clk_late_init(void)
+{
+	if (ck_dpll1.rate >= OMAP1_DPLL1_SANE_VALUE)
+		return;
+
+	/* Find the highest supported frequency and enable it */
+	if (omap1_select_table_rate(&virtual_ck_mpu, ~0)) {
+		pr_err("System frequencies not set, using default. Check your config.\n");
+		omap_writew(0x2290, DPLL_CTL);
+		omap_writew(cpu_is_omap7xx() ? 0x3005 : 0x1005, ARM_CKCTL);
+		ck_dpll1.rate = OMAP1_DPLL1_SANE_VALUE;
+	}
+	propagate_rate(&ck_dpll1);
+	omap1_show_rates();
+}

arch/arm/mach-omap1/devices.c

@@ -30,6 +30,8 @@
 #include <plat/omap7xx.h>
 #include <plat/mcbsp.h>
 
+#include "clock.h"
+
 /*-------------------------------------------------------------------------*/
 
 #if defined(CONFIG_RTC_DRV_OMAP) || defined(CONFIG_RTC_DRV_OMAP_MODULE)
@@ -293,6 +295,7 @@ static int __init omap1_init_devices(void)
 		return -ENODEV;
 
 	omap_sram_init();
+	omap1_clk_late_init();
 
 	/* please keep these calls, and their implementations above,
 	 * in alphabetical order so they're easier to sort through.