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power: reset: at91-poweroff: timely shutdown LPDDR memories 

LPDDR memories can only handle up to 400 uncontrolled power off. Ensure the
proper power off sequence is used before shutting down the platform.

Cc: <stable@vger.kernel.org> # 4.4+
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
This commit is contained in:
Alexandre Belloni 2016-10-25 11:37:59 +02:00 committed by Sebastian Reichel
parent e3f0a4017c
commit 0b0408745e
3 changed files with 102 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/power/reset/Kconfig
View File

@ -32,7 +32,7 @@ config POWER_RESET_AT91_RESET
config POWER_RESET_AT91_SAMA5D2_SHDWC
tristate "Atmel AT91 SAMA5D2-Compatible shutdown controller driver"
depends on ARCH_AT91 || COMPILE_TEST
depends on ARCH_AT91
default SOC_SAMA5
help
This driver supports the alternate shutdown controller for some Atmel

54
drivers/power/reset/at91-poweroff.c
View File

@ -14,9 +14,12 @@
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <soc/at91/at91sam9_ddrsdr.h>
#define AT91_SHDW_CR 0x00 /* Shut Down Control Register */
#define AT91_SHDW_SHDW BIT(0) /* Shut Down command */
#define AT91_SHDW_KEY (0xa5 << 24) /* KEY Password */
@ -50,6 +53,7 @@ static const char *shdwc_wakeup_modes[] = {
static void __iomem *at91_shdwc_base;
static struct clk *sclk;
static void __iomem *mpddrc_base;
static void __init at91_wakeup_status(void)
{
@ -73,6 +77,29 @@ static void at91_poweroff(void)
writel(AT91_SHDW_KEY | AT91_SHDW_SHDW, at91_shdwc_base + AT91_SHDW_CR);
}
static void at91_lpddr_poweroff(void)
{
asm volatile(
/* Align to cache lines */
".balign 32\n\t"
/* Ensure AT91_SHDW_CR is in the TLB by reading it */
" ldr r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
/* Power down SDRAM0 */
" str %1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
/* Shutdown CPU */
" str %3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
" b .\n\t"
:
: "r" (mpddrc_base),
"r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
"r" (at91_shdwc_base),
"r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW)
: "r0");
}
static int at91_poweroff_get_wakeup_mode(struct device_node *np)
{
const char *pm;
@ -124,6 +151,8 @@ static void at91_poweroff_dt_set_wakeup_mode(struct platform_device *pdev)
static int __init at91_poweroff_probe(struct platform_device *pdev)
{
struct resource *res;
struct device_node *np;
u32 ddr_type;
int ret;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@ -150,12 +179,30 @@ static int __init at91_poweroff_probe(struct platform_device *pdev)
pm_power_off = at91_poweroff;
np = of_find_compatible_node(NULL, NULL, "atmel,sama5d3-ddramc");
if (!np)
return 0;
mpddrc_base = of_iomap(np, 0);
of_node_put(np);
if (!mpddrc_base)
return 0;
ddr_type = readl(mpddrc_base + AT91_DDRSDRC_MDR) & AT91_DDRSDRC_MD;
if ((ddr_type == AT91_DDRSDRC_MD_LPDDR2) ||
(ddr_type == AT91_DDRSDRC_MD_LPDDR3))
pm_power_off = at91_lpddr_poweroff;
else
iounmap(mpddrc_base);
return 0;
}
static int __exit at91_poweroff_remove(struct platform_device *pdev)
{
if (pm_power_off == at91_poweroff)
if (pm_power_off == at91_poweroff ||
pm_power_off == at91_lpddr_poweroff)
pm_power_off = NULL;
clk_disable_unprepare(sclk);
@ -163,6 +210,11 @@ static int __exit at91_poweroff_remove(struct platform_device *pdev)
return 0;
}
static const struct of_device_id at91_ramc_of_match[] = {
{ .compatible = "atmel,sama5d3-ddramc", },
{ /* sentinel */ }
};
static const struct of_device_id at91_poweroff_of_match[] = {
{ .compatible = "atmel,at91sam9260-shdwc", },
{ .compatible = "atmel,at91sam9rl-shdwc", },

49
drivers/power/reset/at91-sama5d2_shdwc.c
View File

@ -22,9 +22,12 @@
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <soc/at91/at91sam9_ddrsdr.h>
#define SLOW_CLOCK_FREQ 32768
#define AT91_SHDW_CR 0x00 /* Shut Down Control Register */
@ -75,6 +78,7 @@ struct shdwc {
*/
static struct shdwc *at91_shdwc;
static struct clk *sclk;
static void __iomem *mpddrc_base;
static const unsigned long long sdwc_dbc_period[] = {
0, 3, 32, 512, 4096, 32768,
@ -108,6 +112,29 @@ static void at91_poweroff(void)
at91_shdwc->at91_shdwc_base + AT91_SHDW_CR);
}
static void at91_lpddr_poweroff(void)
{
asm volatile(
/* Align to cache lines */
".balign 32\n\t"
/* Ensure AT91_SHDW_CR is in the TLB by reading it */
" ldr r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
/* Power down SDRAM0 */
" str %1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
/* Shutdown CPU */
" str %3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
" b .\n\t"
:
: "r" (mpddrc_base),
"r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
"r" (at91_shdwc->at91_shdwc_base),
"r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW)
: "r0");
}
static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
u32 in_period_us)
{
@ -212,6 +239,8 @@ static int __init at91_shdwc_probe(struct platform_device *pdev)
{
struct resource *res;
const struct of_device_id *match;
struct device_node *np;
u32 ddr_type;
int ret;
if (!pdev->dev.of_node)
@ -249,6 +278,23 @@ static int __init at91_shdwc_probe(struct platform_device *pdev)
pm_power_off = at91_poweroff;
np = of_find_compatible_node(NULL, NULL, "atmel,sama5d3-ddramc");
if (!np)
return 0;
mpddrc_base = of_iomap(np, 0);
of_node_put(np);
if (!mpddrc_base)
return 0;
ddr_type = readl(mpddrc_base + AT91_DDRSDRC_MDR) & AT91_DDRSDRC_MD;
if ((ddr_type == AT91_DDRSDRC_MD_LPDDR2) ||
(ddr_type == AT91_DDRSDRC_MD_LPDDR3))
pm_power_off = at91_lpddr_poweroff;
else
iounmap(mpddrc_base);
return 0;
}
@ -256,7 +302,8 @@ static int __exit at91_shdwc_remove(struct platform_device *pdev)
{
struct shdwc *shdw = platform_get_drvdata(pdev);
if (pm_power_off == at91_poweroff)
if (pm_power_off == at91_poweroff ||
pm_power_off == at91_lpddr_poweroff)
pm_power_off = NULL;
/* Reset values to disable wake-up features */