Date:	Thu, 2 Oct 2014 16:16:27 -0500
From:	atull <atull@...nsource.altera.com>
To:	<dinguyen@...nsource.altera.com>, <linux@....linux.org.uk>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <delicious.quinoa@...il.com>,
	<yvanderv@...nsource.altera.com>
Subject: Re: [PATCH v2 2/2] socfpga: support suspend to ram

On Wed, 1 Oct 2014, atull@...nsource.altera.com wrote:

> From: Alan Tull <atull@...nsource.altera.com>
> 
> Add code that requests that the sdr controller go into
> self-refresh mode.  This code is run from ocram.
> 
> This patch assumes that u-boot has already configured sdr:
>   sdr.ctrlcfg.lowpwreq.selfrfshmask = 3
>   sdr.ctrlcfg.lowpwrtiming.clkdisablecycles = 8
>   sdr.ctrlcfg.dramtiming4.selfrfshexit = 512
> 
> How to suspend to ram:
>  $ echo enabled > \
> /sys/devices/soc/ffc02000.serial0/tty/ttyS0/power/wakeup
> 
>  $ echo -n mem > /sys/power/state
> 
> Signed-off-by: Alan Tull <atull@...nsource.altera.com>
> 
> v2: use Generic on-chip SRAM driver to allocate ocram
>     rm fncpy_align since generic allocator handles alignment
>     check __arm_ioremap_exec return code
>     check for NULL pointers
>     add a comment regarding sdram controller configuration
> ---
>  arch/arm/mach-socfpga/Kconfig        |    1 +
>  arch/arm/mach-socfpga/Makefile       |    1 +
>  arch/arm/mach-socfpga/core.h         |    6 +-
>  arch/arm/mach-socfpga/platsmp.c      |    4 +-
>  arch/arm/mach-socfpga/pm.c           |  147 +++++++++++++++++++++++++++++++
>  arch/arm/mach-socfpga/self-refresh.S |  157 ++++++++++++++++++++++++++++++++++
>  arch/arm/mach-socfpga/socfpga.c      |   10 +++
>  7 files changed, 323 insertions(+), 3 deletions(-)
>  create mode 100644 arch/arm/mach-socfpga/pm.c
>  create mode 100644 arch/arm/mach-socfpga/self-refresh.S
> 
> diff --git a/arch/arm/mach-socfpga/Kconfig b/arch/arm/mach-socfpga/Kconfig
> index b5f8d75..81449da 100644
> --- a/arch/arm/mach-socfpga/Kconfig
> +++ b/arch/arm/mach-socfpga/Kconfig
> @@ -4,6 +4,7 @@ config ARCH_SOCFPGA
>  	select ARM_GIC
>  	select CACHE_L2X0
>  	select DW_APB_TIMER_OF
> +	select GENERIC_ALLOCATOR
>  	select GPIO_PL061 if GPIOLIB
>  	select HAVE_ARM_SCU
>  	select HAVE_ARM_TWD if SMP
> diff --git a/arch/arm/mach-socfpga/Makefile b/arch/arm/mach-socfpga/Makefile
> index 6dd7a93..0591927 100644
> --- a/arch/arm/mach-socfpga/Makefile
> +++ b/arch/arm/mach-socfpga/Makefile
> @@ -4,3 +4,4 @@
>  
>  obj-y					:= socfpga.o
>  obj-$(CONFIG_SMP)	+= headsmp.o platsmp.o
> +obj-$(CONFIG_SUSPEND)	+= pm.o self-refresh.o
> diff --git a/arch/arm/mach-socfpga/core.h b/arch/arm/mach-socfpga/core.h
> index 953a9c0..211adfd 100644
> --- a/arch/arm/mach-socfpga/core.h
> +++ b/arch/arm/mach-socfpga/core.h
> @@ -21,7 +21,7 @@
>  #define __MACH_CORE_H
>  
>  #define SOCFPGA_RSTMGR_CTRL	0x04
> -#define SOCFPGA_RSTMGR_MODMPURST	0x10
> +#define SOCFPGA_RSTMGR_MPUMODRST	0x10

Obvious error here - I ment to change the name of the #define where I 
added it in patch 1, not add it in patch 1 and change it in patch 2.

Alan

>  #define SOCFPGA_RSTMGR_MODPERRST	0x14
>  #define SOCFPGA_RSTMGR_BRGMODRST	0x1c
>  
> @@ -39,6 +39,7 @@ extern void socfpga_sysmgr_init(void);
>  
>  extern void __iomem *sys_manager_base_addr;
>  extern void __iomem *rst_manager_base_addr;
> +extern void __iomem *sdr_ctl_base_addr;
>  
>  extern struct smp_operations socfpga_smp_ops;
>  extern char secondary_trampoline, secondary_trampoline_end;
> @@ -47,4 +48,7 @@ extern unsigned long cpu1start_addr;
>  
>  #define SOCFPGA_SCU_VIRT_BASE   0xfffec000
>  
> +u32 socfpga_sdram_self_refresh(u32 sdr_base, u32 scu_base);
> +extern unsigned int socfpga_sdram_self_refresh_sz;
> +
>  #endif
> diff --git a/arch/arm/mach-socfpga/platsmp.c b/arch/arm/mach-socfpga/platsmp.c
> index 97907dd..4093852 100644
> --- a/arch/arm/mach-socfpga/platsmp.c
> +++ b/arch/arm/mach-socfpga/platsmp.c
> @@ -36,7 +36,7 @@ static int socfpga_boot_secondary(unsigned int cpu, struct task_struct *idle)
>  	if (cpu1start_addr) {
>  		/* This will put CPU #1 into reset. */
>  		__raw_writel(RSTMGR_MPUMODRST_CPU1,
> -			     rst_manager_base_addr + SOCFPGA_RSTMGR_MODMPURST);
> +			     rst_manager_base_addr + SOCFPGA_RSTMGR_MPUMODRST);
>  
>  		memcpy(phys_to_virt(0), &secondary_trampoline, trampoline_size);
>  
> @@ -49,7 +49,7 @@ static int socfpga_boot_secondary(unsigned int cpu, struct task_struct *idle)
>  
>  		/* This will release CPU #1 out of reset. */
>  		__raw_writel(0,
> -			     rst_manager_base_addr + SOCFPGA_RSTMGR_MODMPURST);
> +			     rst_manager_base_addr + SOCFPGA_RSTMGR_MPUMODRST);
>  	}
>  
>  	return 0;
> diff --git a/arch/arm/mach-socfpga/pm.c b/arch/arm/mach-socfpga/pm.c
> new file mode 100644
> index 0000000..912aab8
> --- /dev/null
> +++ b/arch/arm/mach-socfpga/pm.c
> @@ -0,0 +1,147 @@
> +/*
> + *  arch/arm/mach-socfpga/pm.c
> + *
> + * Copyright (C) 2014 Altera Corporation. All rights reserved.
> + *
> + * with code from pm-imx6.c
> + * Copyright 2011-2014 Freescale Semiconductor, Inc.
> + * Copyright 2011 Linaro Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/genalloc.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/of_platform.h>
> +#include <linux/suspend.h>
> +#include <asm/suspend.h>
> +#include <asm/fncpy.h>
> +#include "core.h"
> +
> +/* Pointer to function copied to ocram */
> +static u32 (*socfpga_sdram_self_refresh_in_ocram)(u32 sdr_base, u32 scu_base);
> +
> +static int socfpga_setup_ocram_self_refresh(void)
> +{
> +	struct platform_device *pdev;
> +	phys_addr_t ocram_pbase;
> +	struct device_node *np;
> +	struct gen_pool *ocram_pool;
> +	unsigned long ocram_base;
> +	void __iomem *suspend_ocram_base;
> +	int ret = 0;
> +
> +	np = of_find_compatible_node(NULL, NULL, "mmio-sram");
> +	if (!np) {
> +		pr_err("%s: Unable to find mmio-sram in dtb\n", __func__);
> +		return 0;
> +	}
> +
> +	pdev = of_find_device_by_node(np);
> +	if (!pdev) {
> +		pr_warn("%s: failed to find ocram device!\n", __func__);
> +		ret = -ENODEV;
> +		goto put_node;
> +	}
> +
> +	ocram_pool = dev_get_gen_pool(&pdev->dev);
> +	if (!ocram_pool) {
> +		pr_warn("%s: ocram pool unavailable!\n", __func__);
> +		ret = -ENODEV;
> +		goto put_node;
> +	}
> +
> +	ocram_base = gen_pool_alloc(ocram_pool, socfpga_sdram_self_refresh_sz);
> +	if (!ocram_base) {
> +		pr_warn("%s: unable to alloc ocram!\n", __func__);
> +		ret = -ENOMEM;
> +		goto put_node;
> +	}
> +
> +	ocram_pbase = gen_pool_virt_to_phys(ocram_pool, ocram_base);
> +
> +	suspend_ocram_base = __arm_ioremap_exec(ocram_pbase,
> +						socfpga_sdram_self_refresh_sz,
> +						false);
> +	if (!suspend_ocram_base) {
> +		pr_warn("%s: __arm_ioremap_exec failed!\n", __func__);
> +		ret = -ENOMEM;
> +		goto put_node;
> +	}
> +
> +	/* Copy the code that puts DDR in self refresh to ocram */
> +	socfpga_sdram_self_refresh_in_ocram =
> +		(void *)fncpy(suspend_ocram_base,
> +			      &socfpga_sdram_self_refresh,
> +			      socfpga_sdram_self_refresh_sz);
> +
> +	WARN(!socfpga_sdram_self_refresh_in_ocram,
> +	     "could not copy function to ocram");
> +	if (!socfpga_sdram_self_refresh_in_ocram)
> +		ret = -EFAULT;
> +
> +put_node:
> +	of_node_put(np);
> +
> +	return ret;
> +}
> +
> +static int socfpga_pm_suspend(unsigned long arg)
> +{
> +	u32 ret;
> +
> +	if (!sdr_ctl_base_addr || !socfpga_scu_base_addr)
> +		return -EFAULT;
> +
> +	ret = socfpga_sdram_self_refresh_in_ocram(
> +		(u32)sdr_ctl_base_addr, (u32)socfpga_scu_base_addr);
> +
> +	pr_debug("%s self-refresh loops request=%d exit=%d\n", __func__,
> +		 ret & 0xffff, (ret >> 16) & 0xffff);
> +
> +	return 0;
> +}
> +
> +static int socfpga_pm_enter(suspend_state_t state)
> +{
> +	switch (state) {
> +	case PM_SUSPEND_STANDBY:
> +	case PM_SUSPEND_MEM:
> +		outer_disable();
> +		cpu_suspend(0, socfpga_pm_suspend);
> +		outer_resume();
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +static const struct platform_suspend_ops socfpga_pm_ops = {
> +	.valid	= suspend_valid_only_mem,
> +	.enter	= socfpga_pm_enter,
> +};
> +
> +static int __init socfpga_pm_init(void)
> +{
> +	if (socfpga_setup_ocram_self_refresh())
> +		return -EFAULT;
> +
> +	suspend_set_ops(&socfpga_pm_ops);
> +	pr_info("SoCFPGA initialized for DDR self-refresh during suspend.\n");
> +
> +	return 0;
> +}
> +arch_initcall(socfpga_pm_init);
> diff --git a/arch/arm/mach-socfpga/self-refresh.S b/arch/arm/mach-socfpga/self-refresh.S
> new file mode 100644
> index 0000000..93962d4
> --- /dev/null
> +++ b/arch/arm/mach-socfpga/self-refresh.S
> @@ -0,0 +1,157 @@
> +/*
> + * Copyright (C) 2014 Altera Corporation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
> + */
> +#include <linux/linkage.h>
> +#include <asm/assembler.h>
> +
> +#define SOCFPGA_SCU_CTRL_OFFS	0
> +#define SCU_STANDBY_ENA		0x20
> +#define MAX_LOOP_COUNT		1000
> +
> +/* Register offset */
> +#define SDR_CTRLGRP_LOWPWREQ_ADDR       0x54
> +#define SDR_CTRLGRP_LOWPWRACK_ADDR      0x58
> +
> +/* Bitfield positions */
> +#define SELFRSHREQ_POS                  3
> +#define SELFRSHREQ_MASK                 0x8
> +
> +#define SELFRFSHACK_POS                 1
> +#define SELFRFSHACK_MASK                0x2
> +
> +	/*	
> +	 * This code assumes that the bootloader has already
> +	 * properly configured the sdram controller:
> +	 *
> +	 * sdr.ctrlcfg.lowpwreq.selfrfshmask = 3
> +	 * sdr.ctrlcfg.lowpwrtiming.clkdisablecycles = 8
> +	 * sdr.ctrlcfg.dramtiming4.selfrfshexit = 512
> +	 */
> +
> +	.arch   armv7-a
> +	.text
> +	.align 3
> +
> +	/*
> +	 * socfpga_sdram_self_refresh
> +	 *
> +	 *  r0 : sdr_ctl_base_addr
> +	 *  r1 : socfpga_scu_base_addr
> +	 *  r2 : temp storage of register values
> +	 *  r3 : loop counter
> +	 *  r4 : temp storage of return value
> +	 *
> +	 *  return value: lower 16 bits: loop count going into self refresh
> +	 *                upper 16 bits: loop count exiting self refresh
> +	 */
> +ENTRY(socfpga_sdram_self_refresh)
> +	stmfd	sp!, {r4}
> +
> +	/*
> +	 * Enable SCU (snoop) standby mode.
> +	 *
> +	 * From the ARM Cortex-A9 MPCore Technical Reference Manual:
> +	 * "When set, SCU CLK is turned off when all processors are in WFI
> +	 *  mode, there is no pending request on the ACP (if implemented), and
> +	 *  there is no remaining activity in the SCU."
> +	 */
> +	ldr	r2, [r1, #SOCFPGA_SCU_CTRL_OFFS]
> +	orr	r2, r2, #SCU_STANDBY_ENA
> +	str	r2, [r1, #SOCFPGA_SCU_CTRL_OFFS]
> +
> +	/* Enable dynamic clock gating in the Power Control Register. */
> +	mrc	p15, 0, r2, c15, c0, 0
> +	orr	r2, r2, #1
> +	mcr	p15, 0, r2, c15, c0, 0
> +
> +	/* Enable self refresh: set sdr.ctrlgrp.lowpwreq.selfrshreq = 1 */
> +	ldr	r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR]
> +	orr	r2, r2, #SELFRSHREQ_MASK
> +	str	r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR]
> +
> +	/* Poll until sdr.ctrlgrp.lowpwrack.selfrfshack == 1 or hit max loops */
> +	mov	r3, #0
> +while_ack_0:
> +	ldr	r2, [r0, #SDR_CTRLGRP_LOWPWRACK_ADDR]
> +	and	r2, r2, #SELFRFSHACK_MASK
> +	cmp	r2, #SELFRFSHACK_MASK
> +	beq	ack_1
> +
> +	add	r3, #1
> +	cmp	r3, #MAX_LOOP_COUNT
> +	bne	while_ack_0
> +
> +ack_1:
> +	mov	r4, r3
> +
> +	/*
> +	 * Execute an ISB instruction to ensure that all of the
> +	 * CP15 register changes have been committed.
> +	 */
> +	isb
> +
> +	/*
> +	 * Execute a barrier instruction to ensure that all cache,
> +	 * TLB and branch predictor maintenance operations issued
> +	 * by any CPU in the cluster have completed.
> +	 */
> +	dsb
> +	dmb
> +
> +	wfi
> +
> +	/* Disable self-refresh: set sdr.ctrlgrp.lowpwreq.selfrshreq = 0 */
> +	ldr	r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR]
> +	bic	r2, r2, #SELFRSHREQ_MASK
> +	str	r2, [r0, #SDR_CTRLGRP_LOWPWREQ_ADDR]
> +
> +	/* Poll until sdr.ctrlgrp.lowpwrack.selfrfshack == 0 or hit max loops */
> +	mov	r3, #0
> +while_ack_1:
> +	ldr	r2, [r0, #SDR_CTRLGRP_LOWPWRACK_ADDR]
> +	and	r2, r2, #SELFRFSHACK_MASK
> +	cmp	r2, #SELFRFSHACK_MASK
> +	bne	ack_0
> +
> +	add	r3, #1
> +	cmp	r3, #MAX_LOOP_COUNT
> +	bne	while_ack_1
> +
> +ack_0:
> +	/*
> +	 * Prepare return value:
> +	 * Shift loop count for exiting self refresh into upper 16 bits.
> +	 * Leave loop count for requesting self refresh in lower 16 bits.
> +	 */
> +	mov	r3, r3, lsl #16
> +	add	r4, r4, r3
> +
> +	/* Disable dynamic clock gating in the Power Control Register. */
> +	mrc	p15, 0, r2, c15, c0, 0
> +	bic	r2, r2, #1
> +	mcr	p15, 0, r2, c15, c0, 0
> +
> +	/* Disable SCU standby mode */
> +	ldr	r2, [r1, #SOCFPGA_SCU_CTRL_OFFS]
> +	bic	r2, r2, #SCU_STANDBY_ENA
> +	str	r2, [r1, #SOCFPGA_SCU_CTRL_OFFS]
> +
> +	mov     r0, r4                  @ return value
> +	ldmfd	sp!, {r4}
> +	bx	lr			@ return
> +
> +ENDPROC(socfpga_sdram_self_refresh)
> +ENTRY(socfpga_sdram_self_refresh_sz)
> +	.word	. - socfpga_sdram_self_refresh
> diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
> index adbf383..34b4cc5 100644
> --- a/arch/arm/mach-socfpga/socfpga.c
> +++ b/arch/arm/mach-socfpga/socfpga.c
> @@ -30,6 +30,7 @@ void __iomem *socfpga_scu_base_addr = ((void __iomem *)(SOCFPGA_SCU_VIRT_BASE));
>  void __iomem *sys_manager_base_addr;
>  void __iomem *rst_manager_base_addr;
>  unsigned long cpu1start_addr;
> +void __iomem *sdr_ctl_base_addr;
>  
>  static struct map_desc scu_io_desc __initdata = {
>  	.virtual	= SOCFPGA_SCU_VIRT_BASE,
> @@ -77,6 +78,15 @@ void __init socfpga_sysmgr_init(void)
>  
>  	np = of_find_compatible_node(NULL, NULL, "altr,rst-mgr");
>  	rst_manager_base_addr = of_iomap(np, 0);
> +
> +	np = of_find_compatible_node(NULL, NULL, "altr,sdr-ctl");
> +	if (!np) {
> +		pr_err("SOCFPGA: Unable to find sdr-ctl\n");
> +		return;
> +	}
> +
> +	sdr_ctl_base_addr = of_iomap(np, 0);
> +	WARN_ON(!sdr_ctl_base_addr);
>  }
>  
>  static void __init socfpga_init_irq(void)
> -- 
> 1.7.9.5
> 
> 
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