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Date:	Thu, 23 Oct 2014 09:59:44 -0500
From:	Dinh Nguyen <dinguyen@...nsource.altera.com>
To:	<atull@...nsource.altera.com>, <linux@....linux.org.uk>
CC:	<pavel@...x.de>, <arnd@...db.de>, <s.trumtrar@...gutronix.de>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <delicious.quinoa@...il.com>,
	<yvanderv@...nsource.altera.com>
Subject: Re: [PATCH v3 2/2] socfpga: support suspend to ram

Hi Alan,

On 10/14/2014 02:33 PM, 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>
> Cc: Pavel Machek <pavel@...x.de>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Dinh Nguyen <dinguyen@...nsource.altera.com>
> Cc: Steffen Trumtrar <s.trumtrar@...gutronix.de>
> ---
> 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
> v3: fix renamed #define
>     propagate socfpga_setup_ocram_self_refresh error code
> ---
>  arch/arm/mach-socfpga/Kconfig        |    1 +
>  arch/arm/mach-socfpga/Makefile       |    1 +
>  arch/arm/mach-socfpga/core.h         |    4 +
>  arch/arm/mach-socfpga/pm.c           |  150 ++++++++++++++++++++++++++++++++
>  arch/arm/mach-socfpga/self-refresh.S |  157 ++++++++++++++++++++++++++++++++++
>  arch/arm/mach-socfpga/socfpga.c      |   10 +++
>  6 files changed, 323 insertions(+)
>  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..baa8392 100644
> --- a/arch/arm/mach-socfpga/core.h
> +++ b/arch/arm/mach-socfpga/core.h
> @@ -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/pm.c b/arch/arm/mach-socfpga/pm.c
> new file mode 100644
> index 0000000..486f018
> --- /dev/null
> +++ b/arch/arm/mach-socfpga/pm.c
> @@ -0,0 +1,150 @@
> +/*
> + *  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)
> +{
> +	int ret;
> +
> +	ret = socfpga_setup_ocram_self_refresh();
> +	if (ret)
> +		return ret;
> +
> +	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)
> 

When I went to apply this, I noticed that the "altr,sdr-ctl" binding has
not yet been defined anywhere. It looks like like you are using this
binding to get the base address of the SDRAM controller for the
self-refresh code. Since the self-refresh code is very specific to the
SOCFPGA platform, would it be easier to define the SDRAM controller's
base address in the assembly? If not, then you will have to define the
"altr,adr-ctl" binding.


Dinh
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