Hello Mario,
On 20/10/2021 11:29:46-0500, Mario Limonciello wrote:
> RTC based wakeup from s0i3 doesn't work properly on some Green Sardine
> platforms. Because of this, a newer SMU for Green Sardine has the ability
> to pass wakeup time as argument of the upper 16 bits of OS_HINT message.
>
> With older firmware setting the timer value in OS_HINT will cause firmware
> to reject the hint, so only run this path on:
> 1) Green Sardine
> 2) Minimum SMU FW
> 3) RTC alarm armed during s0i3 entry
>
> Using this method has some limitations that the s0i3 wakeup will need to
> be between 4 seconds and 18 hours, so check those boundary conditions as
> well and abort the suspend if RTC is armed for too short or too long of a
> duration.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> drivers/platform/x86/amd-pmc.c | 60 +++++++++++++++++++++++++++++++++-
> 1 file changed, 59 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/amd-pmc.c b/drivers/platform/x86/amd-pmc.c
> index 99ac50616bc3..678bf6874c63 100644
> --- a/drivers/platform/x86/amd-pmc.c
> +++ b/drivers/platform/x86/amd-pmc.c
> @@ -17,9 +17,11 @@
> #include <linux/delay.h>
> #include <linux/io.h>
> #include <linux/iopoll.h>
> +#include <linux/limits.h>
> #include <linux/module.h>
> #include <linux/pci.h>
> #include <linux/platform_device.h>
> +#include <linux/rtc.h>
> #include <linux/suspend.h>
> #include <linux/seq_file.h>
> #include <linux/uaccess.h>
> @@ -412,20 +414,76 @@ static int amd_pmc_get_os_hint(struct amd_pmc_dev *dev)
> return -EINVAL;
> }
>
> +static int amd_pmc_verify_czn_rtc(struct amd_pmc_dev *pdev, u32 *arg)
> +{
> + struct rtc_device *rtc_device;
> + time64_t then, now, duration;
> + struct rtc_wkalrm alarm;
> + struct rtc_time tm;
> + int rc;
> +
> + if (pdev->major < 64 || (pdev->major == 64 && pdev->minor < 53))
> + return 0;
> +
> + rtc_device = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
No this will not work as you can see in your and Arnd's patch adding
ifdefery to handle RTC_SYSTOHC_DEVICE not being set. You have no
guarantee that RTC_SYSTOHC_DEVICE is the device you are looking for. You
need to rework that part.
> + if (!rtc_device)
> + return 0;
> + rc = rtc_read_alarm(rtc_device, &alarm);
> + if (rc)
> + return rc;
> + if (!alarm.enabled) {
> + dev_dbg(pdev->dev, "alarm not enabled\n");
> + return 0;
> + }
> + rc = rtc_valid_tm(&alarm.time);
> + if (rc)
> + return rc;
Why do you think the RTC core give you an invalid alarm time?
> + rc = rtc_read_time(rtc_device, &tm);
> + if (rc)
> + return rc;
> + then = rtc_tm_to_time64(&alarm.time);
> + now = rtc_tm_to_time64(&tm);
> + duration = then-now;
> +
> + /* in the past */
> + if (then < now)
> + return 0;
> +
> + /* will be stored in upper 16 bits of s0i3 hint argument,
> + * so timer wakeup from s0i3 is limited to ~18 hours or less
> + */
> + if (duration <= 4 || duration > U16_MAX)
> + return -EINVAL;
> +
> + *arg |= (duration << 16);
> + rc = rtc_alarm_irq_enable(rtc_device, 0);
What if userspace is waiting for the alarm to happen?
> + dev_info(pdev->dev, "wakeup timer programmed for %lld seconds\n", duration);
> +
Do you actually need this message, looks like leftover debug to me?
> + return rc;
> +}
> +
> static int __maybe_unused amd_pmc_suspend(struct device *dev)
> {
> struct amd_pmc_dev *pdev = dev_get_drvdata(dev);
> int rc;
> u8 msg;
> + u32 arg = 1;
>
> /* Reset and Start SMU logging - to monitor the s0i3 stats */
> amd_pmc_send_cmd(pdev, 0, NULL, SMU_MSG_LOG_RESET, 0);
> amd_pmc_send_cmd(pdev, 0, NULL, SMU_MSG_LOG_START, 0);
>
> + /* Activate CZN specific RTC functionality */
> + if (pdev->cpu_id == AMD_CPU_ID_CZN) {
> + rc = amd_pmc_verify_czn_rtc(pdev, &arg);
> + if (rc < 0)
> + return rc;
> + }
> +
> /* Dump the IdleMask before we send hint to SMU */
> amd_pmc_idlemask_read(pdev, dev, NULL);
> msg = amd_pmc_get_os_hint(pdev);
> - rc = amd_pmc_send_cmd(pdev, 1, NULL, msg, 0);
> + rc = amd_pmc_send_cmd(pdev, arg, NULL, msg, 0);
> if (rc)
> dev_err(pdev->dev, "suspend failed\n");
>
> --
> 2.25.1
>
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
