x86/platform/atom: Check state of Punit managed devices on s2idle

For the Bay Trail or Cherry Trail SoC to enter the S0i3 power-level
at s2idle suspend requires most of the hw-blocks / devices in the SoC
to be in D3 when entering s2idle suspend.

If some devices are not in D3 then the SoC will stay in a higher
power state, consuming much more power from the battery then in S0i3.

Use the new acpi_s2idle_dev_ops and acpi_register_lps0_dev()
functionality to register a new s2idle check function which checks that
all hardware blocks in the North complex (controlled by Punit) are in
a state that allows the SoC to enter S0i3 and prints an error message
for any device in D0.

Signed-off-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: "Borislav Petkov (AMD)" <bp@alien8.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
[hdegoede: Use acpi_s2idle_dev_ops]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240305105915.76242-6-hdegoede@redhat.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: js202510

arch/x86/platform/atom/punit_atom_debug.c

@@ -7,6 +7,9 @@
  * Copyright (c) 2015, Intel Corporation.
  */
 
+#define pr_fmt(fmt) "punit_atom: " fmt
+
+#include <linux/acpi.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/device.h>
@@ -117,6 +120,51 @@ static void punit_dbgfs_unregister(void)
 	debugfs_remove_recursive(punit_dbg_file);
 }
 
+#if defined(CONFIG_ACPI) && defined(CONFIG_SUSPEND)
+static const struct punit_device *punit_dev;
+
+static void punit_s2idle_check(void)
+{
+	const struct punit_device *punit_devp;
+	u32 punit_pwr_status, dstate;
+	int status;
+
+	for (punit_devp = punit_dev; punit_devp->name; punit_devp++) {
+		/* Skip MIO, it is on till the very last moment */
+		if (punit_devp->reg == MIO_SS_PM)
+			continue;
+
+		status = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ,
+				       punit_devp->reg, &punit_pwr_status);
+		if (status) {
+			pr_err("%s read failed\n", punit_devp->name);
+		} else  {
+			dstate = (punit_pwr_status >> punit_devp->sss_pos) & 3;
+			if (!dstate)
+				pr_err("%s is in D0 prior to s2idle\n", punit_devp->name);
+		}
+	}
+}
+
+static struct acpi_s2idle_dev_ops punit_s2idle_ops = {
+	.check = punit_s2idle_check,
+};
+
+static void punit_s2idle_check_register(struct punit_device *punit_device)
+{
+	punit_dev = punit_device;
+	acpi_register_lps0_dev(&punit_s2idle_ops);
+}
+
+static void punit_s2idle_check_unregister(void)
+{
+	acpi_unregister_lps0_dev(&punit_s2idle_ops);
+}
+#else
+static void punit_s2idle_check_register(struct punit_device *punit_device) {}
+static void punit_s2idle_check_unregister(void) {}
+#endif
+
 #define X86_MATCH(model, data)						 \
 	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6, INTEL_FAM6_##model, \
 					   X86_FEATURE_MWAIT, data)
@@ -131,19 +179,23 @@ MODULE_DEVICE_TABLE(x86cpu, intel_punit_cpu_ids);
 
 static int __init punit_atom_debug_init(void)
 {
+	struct punit_device *punit_device;
 	const struct x86_cpu_id *id;
 
 	id = x86_match_cpu(intel_punit_cpu_ids);
 	if (!id)
 		return -ENODEV;
 
-	punit_dbgfs_register((struct punit_device *)id->driver_data);
+	punit_device = (struct punit_device *)id->driver_data;
+	punit_dbgfs_register(punit_device);
+	punit_s2idle_check_register(punit_device);
 
 	return 0;
 }
 
 static void __exit punit_atom_debug_exit(void)
 {
+	punit_s2idle_check_unregister();
 	punit_dbgfs_unregister();
 }