ARM: mach-shmobile: sh7372 Core Standby Suspend-to-RAM

Add sh7372 Core Standby sleep mode support and tie it
in with the shared SH-Mobile ARM suspend code.

The Core Standby mode is the lightest sh7372-specific
sleep mode, cutting power to the ARM core excluding the
L2 cache. Any interrupt source can be used for wakeups.

The low level portion of this code is based on the
TI OMAP sleep code in sleep34xx.S, thanks to them.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/arm/mach-shmobile/Makefile

@@ -32,6 +32,7 @@ obj-$(CONFIG_ARCH_SH73A0)	+= entry-gic.o
 
 # PM objects
 obj-$(CONFIG_SUSPEND)		+= suspend.o
+obj-$(CONFIG_ARCH_SH7372)	+= pm-sh7372.o sleep-sh7372.o
 
 # Board objects
 obj-$(CONFIG_MACH_G3EVM)	+= board-g3evm.o

arch/arm/mach-shmobile/board-ap4evb.c

@@ -1354,6 +1354,7 @@ static void __init ap4evb_init(void)
 
 	hdmi_init_pm_clock();
 	fsi_init_pm_clock();
+	sh7372_pm_init();
 }
 
 static void __init ap4evb_timer_init(void)

arch/arm/mach-shmobile/board-mackerel.c

@@ -1230,6 +1230,7 @@ static void __init mackerel_init(void)
 	platform_add_devices(mackerel_devices, ARRAY_SIZE(mackerel_devices));
 
 	hdmi_init_pm_clock();
+	sh7372_pm_init();
 }
 
 static void __init mackerel_timer_init(void)

arch/arm/mach-shmobile/include/mach/common.h

@@ -31,6 +31,9 @@ extern void sh7372_add_early_devices(void);
 extern void sh7372_add_standard_devices(void);
 extern void sh7372_clock_init(void);
 extern void sh7372_pinmux_init(void);
+extern void sh7372_pm_init(void);
+extern void sh7372_cpu_suspend(void);
+extern void sh7372_cpu_resume(void);
 extern struct clk sh7372_extal1_clk;
 extern struct clk sh7372_extal2_clk;
 

arch/arm/mach-shmobile/pm-sh7372.c

+/*
+ * sh7372 Power management support
+ *
+ *  Copyright (C) 2011 Magnus Damm
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/pm.h>
+#include <linux/suspend.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <asm/system.h>
+#include <asm/io.h>
+#include <asm/tlbflush.h>
+#include <mach/common.h>
+
+#define SMFRAM 0xe6a70000
+#define SYSTBCR 0xe6150024
+#define SBAR 0xe6180020
+#define APARMBAREA 0xe6f10020
+
+#ifdef CONFIG_SUSPEND
+static void sh7372_enter_core_standby(void)
+{
+	void __iomem *smfram = (void __iomem *)SMFRAM;
+
+	__raw_writel(0, APARMBAREA); /* translate 4k */
+	__raw_writel(__pa(sh7372_cpu_resume), SBAR); /* set reset vector */
+	__raw_writel(0x10, SYSTBCR); /* enable core standby */
+
+	__raw_writel(0, smfram + 0x3c); /* clear page table address */
+
+	sh7372_cpu_suspend();
+	cpu_init();
+
+	/* if page table address is non-NULL then we have been powered down */
+	if (__raw_readl(smfram + 0x3c)) {
+		__raw_writel(__raw_readl(smfram + 0x40),
+			     __va(__raw_readl(smfram + 0x3c)));
+
+		flush_tlb_all();
+		set_cr(__raw_readl(smfram + 0x38));
+	}
+
+	__raw_writel(0, SYSTBCR); /* disable core standby */
+	__raw_writel(0, SBAR); /* disable reset vector translation */
+}
+
+static int sh7372_enter_suspend(suspend_state_t suspend_state)
+{
+	sh7372_enter_core_standby();
+	return 0;
+}
+
+static void sh7372_suspend_init(void)
+{
+	shmobile_suspend_ops.enter = sh7372_enter_suspend;
+}
+#else
+static void sh7372_suspend_init(void) {}
+#endif
+
+#define DBGREG1 0xe6100020
+#define DBGREG9 0xe6100040
+
+void __init sh7372_pm_init(void)
+{
+	/* enable DBG hardware block to kick SYSC */
+	__raw_writel(0x0000a500, DBGREG9);
+	__raw_writel(0x0000a501, DBGREG9);
+	__raw_writel(0x00000000, DBGREG1);
+
+	sh7372_suspend_init();
+}

arch/arm/mach-shmobile/sleep-sh7372.S

+/*
+ * sh7372 lowlevel sleep code for "Core Standby Mode"
+ *
+ * Copyright (C) 2011 Magnus Damm
+ *
+ * In "Core Standby Mode" the ARM core is off, but L2 cache is still on
+ *
+ * Based on mach-omap2/sleep34xx.S
+ *
+ * (C) Copyright 2007 Texas Instruments
+ * Karthik Dasu <karthik-dp@ti.com>
+ *
+ * (C) Copyright 2004 Texas Instruments, <www.ti.com>
+ * Richard Woodruff <r-woodruff2@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+#define SMFRAM 0xe6a70000
+
+	.align
+kernel_flush:
+	.word	v7_flush_dcache_all
+
+	.align	3
+ENTRY(sh7372_cpu_suspend)
+	stmfd	sp!, {r0-r12, lr}	@ save registers on stack
+
+	ldr	r8, =SMFRAM
+
+	mov	r4, sp			@ Store sp
+	mrs	r5, spsr		@ Store spsr
+	mov	r6, lr			@ Store lr
+	stmia	r8!, {r4-r6}
+
+	mrc	p15, 0, r4, c1, c0, 2	@ Coprocessor access control register
+	mrc	p15, 0, r5, c2, c0, 0	@ TTBR0
+	mrc	p15, 0, r6, c2, c0, 1	@ TTBR1
+	mrc	p15, 0, r7, c2, c0, 2	@ TTBCR
+	stmia	r8!, {r4-r7}
+
+	mrc	p15, 0, r4, c3, c0, 0	@ Domain access Control Register
+	mrc	p15, 0, r5, c10, c2, 0	@ PRRR
+	mrc	p15, 0, r6, c10, c2, 1	@ NMRR
+	stmia	r8!,{r4-r6}
+
+	mrc	p15, 0, r4, c13, c0, 1	@ Context ID
+	mrc	p15, 0, r5, c13, c0, 2	@ User r/w thread and process ID
+	mrc	p15, 0, r6, c12, c0, 0	@ Secure or NS vector base address
+	mrs	r7, cpsr		@ Store current cpsr
+	stmia	r8!, {r4-r7}
+
+	mrc	p15, 0, r4, c1, c0, 0	@ save control register
+	stmia	r8!, {r4}
+
+	/*
+	 * jump out to kernel flush routine
+	 *  - reuse that code is better
+	 *  - it executes in a cached space so is faster than refetch per-block
+	 *  - should be faster and will change with kernel
+	 *  - 'might' have to copy address, load and jump to it
+	 * Flush all data from the L1 data cache before disabling
+	 * SCTLR.C bit.
+	 */
+	ldr	r1, kernel_flush
+	mov	lr, pc
+	bx	r1
+
+	/*
+	 * Clear the SCTLR.C bit to prevent further data cache
+	 * allocation. Clearing SCTLR.C would make all the data accesses
+	 * strongly ordered and would not hit the cache.
+	 */
+	mrc	p15, 0, r0, c1, c0, 0
+	bic	r0, r0, #(1 << 2)	@ Disable the C bit
+	mcr	p15, 0, r0, c1, c0, 0
+	isb
+
+	/*
+	 * Invalidate L1 data cache. Even though only invalidate is
+	 * necessary exported flush API is used here. Doing clean
+	 * on already clean cache would be almost NOP.
+	 */
+	ldr	r1, kernel_flush
+	blx	r1
+	/*
+	 * The kernel doesn't interwork: v7_flush_dcache_all in particluar will
+	 * always return in Thumb state when CONFIG_THUMB2_KERNEL is enabled.
+	 * This sequence switches back to ARM.  Note that .align may insert a
+	 * nop: bx pc needs to be word-aligned in order to work.
+	 */
+ THUMB(	.thumb		)
+ THUMB(	.align		)
+ THUMB(	bx	pc	)
+ THUMB(	nop		)
+	.arm
+
+	/* Data memory barrier and Data sync barrier */
+	dsb
+	dmb
+
+/*
+ * ===================================
+ * == WFI instruction => Enter idle ==
+ * ===================================
+ */
+	wfi				@ wait for interrupt
+
+/*
+ * ===================================
+ * == Resume path for non-OFF modes ==
+ * ===================================
+ */
+	mrc	p15, 0, r0, c1, c0, 0
+	tst	r0, #(1 << 2)		@ Check C bit enabled?
+	orreq	r0, r0, #(1 << 2)	@ Enable the C bit if cleared
+	mcreq	p15, 0, r0, c1, c0, 0
+	isb
+
+/*
+ * ===================================
+ * == Exit point from non-OFF modes ==
+ * ===================================
+ */
+	ldmfd	sp!, {r0-r12, pc}	@ restore regs and return
+
+	.pool
+
+	.align	12
+	.text
+	.global	sh7372_cpu_resume
+sh7372_cpu_resume:
+
+	mov	r1, #0
+	/*
+	 * Invalidate all instruction caches to PoU
+	 * and flush branch target cache
+	 */
+	mcr	p15, 0, r1, c7, c5, 0
+
+	ldr	r3, =SMFRAM
+
+	ldmia	r3!, {r4-r6}
+	mov	sp, r4			@ Restore sp
+	msr	spsr_cxsf, r5		@ Restore spsr
+	mov	lr, r6			@ Restore lr
+
+	ldmia	r3!, {r4-r7}
+	mcr	p15, 0, r4, c1, c0, 2	@ Coprocessor access Control Register
+	mcr	p15, 0, r5, c2, c0, 0	@ TTBR0
+	mcr	p15, 0, r6, c2, c0, 1	@ TTBR1
+	mcr	p15, 0, r7, c2, c0, 2	@ TTBCR
+
+	ldmia	r3!,{r4-r6}
+	mcr	p15, 0, r4, c3, c0, 0	@ Domain access Control Register
+	mcr	p15, 0, r5, c10, c2, 0	@ PRRR
+	mcr	p15, 0, r6, c10, c2, 1	@ NMRR
+
+	ldmia	r3!,{r4-r7}
+	mcr	p15, 0, r4, c13, c0, 1	@ Context ID
+	mcr	p15, 0, r5, c13, c0, 2	@ User r/w thread and process ID
+	mrc	p15, 0, r6, c12, c0, 0	@ Secure or NS vector base address
+	msr	cpsr, r7		@ store cpsr
+
+	/* Starting to enable MMU here */
+	mrc	p15, 0, r7, c2, c0, 2 	@ Read TTBRControl
+	/* Extract N (0:2) bits and decide whether to use TTBR0 or TTBR1 */
+	and	r7, #0x7
+	cmp	r7, #0x0
+	beq	usettbr0
+ttbr_error:
+	/*
+	 * More work needs to be done to support N[0:2] value other than 0
+	 * So looping here so that the error can be detected
+	 */
+	b	ttbr_error
+
+	.align
+cache_pred_disable_mask:
+	.word	0xFFFFE7FB
+ttbrbit_mask:
+	.word	0xFFFFC000
+table_index_mask:
+	.word	0xFFF00000
+table_entry:
+	.word	0x00000C02
+usettbr0:
+
+	mrc	p15, 0, r2, c2, c0, 0
+	ldr	r5, ttbrbit_mask
+	and	r2, r5
+	mov	r4, pc
+	ldr	r5, table_index_mask
+	and	r4, r5			@ r4 = 31 to 20 bits of pc
+	/* Extract the value to be written to table entry */
+	ldr	r6, table_entry
+	/* r6 has the value to be written to table entry */
+	add	r6, r6, r4
+	/* Getting the address of table entry to modify */
+	lsr	r4, #18
+	/* r2 has the location which needs to be modified */
+	add	r2, r4
+	ldr	r4, [r2]
+	str	r6, [r2] /* modify the table entry */
+
+	mov	r7, r6
+	mov	r5, r2
+	mov	r6, r4
+	/* r5 = original page table address */
+	/* r6 = original page table data */
+
+	mov	r0, #0
+	mcr	p15, 0, r0, c7, c5, 4	@ Flush prefetch buffer
+	mcr	p15, 0, r0, c7, c5, 6	@ Invalidate branch predictor array
+	mcr	p15, 0, r0, c8, c5, 0	@ Invalidate instruction TLB
+	mcr	p15, 0, r0, c8, c6, 0	@ Invalidate data TLB
+
+	/*
+	 * Restore control register. This enables the MMU.
+	 * The caches and prediction are not enabled here, they
+	 * will be enabled after restoring the MMU table entry.
+	 */
+	ldmia	r3!, {r4}
+	stmia	r3!, {r5} /* save original page table address */
+	stmia	r3!, {r6} /* save original page table data */
+	stmia	r3!, {r7} /* save modified page table data */
+
+	ldr	r2, cache_pred_disable_mask
+	and	r4, r2
+	mcr	p15, 0, r4, c1, c0, 0
+	dsb
+	isb
+
+	ldr     r0, =restoremmu_on
+	bx      r0
+
+/*
+ * ==============================
+ * == Exit point from OFF mode ==
+ * ==============================
+ */
+restoremmu_on:
+
+	ldmfd	sp!, {r0-r12, pc}	@ restore regs and return