2016-10-07 18:34 GMT+02:00 Alexandre Belloni
<alexandre.bell...@free-electrons.com>:
> LPDDR memories can only handle up to 400 uncontrolled power off. Ensure the
> proper power off sequence is used before shutting down the platform.
>
> Signed-off-by: Alexandre Belloni <alexandre.bell...@free-electrons.com>
> ---
>  drivers/power/reset/at91-poweroff.c      | 52 
> +++++++++++++++++++++++++++++++-
>  drivers/power/reset/at91-sama5d2_shdwc.c | 48 ++++++++++++++++++++++++++++-
>  2 files changed, 98 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/power/reset/at91-poweroff.c 
> b/drivers/power/reset/at91-poweroff.c
> index e9e24df35f26..bf97390e6cd7 100644
> --- a/drivers/power/reset/at91-poweroff.c
> +++ b/drivers/power/reset/at91-poweroff.c
> @@ -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 +77,28 @@ 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"
> +
> +               "       ldr     r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
At first sight, it looks useless. I assume it's used to preload the
TLB before the LPDDR is turned off.
A comment to explain why this line is useful would prevent its removal.
> +
> +               /* 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 +150,8 @@ 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 +178,29 @@ 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))
Souldn't there be something like "pm_power_off = at91_lpddr_poweroff;" here ?

Jean-Jacques

> +       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 +208,11 @@ 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", },
> diff --git a/drivers/power/reset/at91-sama5d2_shdwc.c 
> b/drivers/power/reset/at91-sama5d2_shdwc.c
> index 8a5ac9706c9c..5736f360b374 100644
> --- a/drivers/power/reset/at91-sama5d2_shdwc.c
> +++ b/drivers/power/reset/at91-sama5d2_shdwc.c
> @@ -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 +112,28 @@ 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"
> +
> +               "       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 +238,8 @@ 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 +277,23 @@ 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 +301,8 @@ 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  */
> --
> 2.9.3
>
>
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