platform/x86: pmc_atom: Check state of PMC 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 South complex (controlled by the PMC)
are in a state that allows the SoC to enter S0i3 and prints an error
message for any device in D0.

Some blocks are not used on lower-featured versions of the SoC and
these blocks will always report being in D0 on SoCs were they are
not used. A false-positive mask is used to identify these blocks
and for blocks in this mask the error is turned into a debug message
to avoid false-positive error messages.

Note the pmc_atom code is enabled by CONFIG_X86_INTEL_LPSS which
already depends on ACPI.

Signed-off-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
[hdegoede: Use acpi_s2idle_dev_ops, ignore fused off blocks, PMIC I2C]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240305105915.76242-4-hdegoede@redhat.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: js202510

drivers/platform/x86/pmc_atom.c

@@ -6,6 +6,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/acpi.h>
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/dmi.h>
@@ -17,6 +18,7 @@
 #include <linux/platform_device.h>
 #include <linux/pci.h>
 #include <linux/seq_file.h>
+#include <linux/suspend.h>
 
 struct pmc_bit_map {
 	const char *name;
@@ -448,6 +450,71 @@ static int pmc_setup_clks(struct pci_dev *pdev, void __iomem *pmc_regmap,
 	return 0;
 }
 
+#ifdef CONFIG_SUSPEND
+static void pmc_dev_state_check(u32 sts, const struct pmc_bit_map *sts_map,
+				u32 fd, const struct pmc_bit_map *fd_map,
+				u32 sts_possible_false_pos)
+{
+	int index;
+
+	for (index = 0; sts_map[index].name; index++) {
+		if (!(fd_map[index].bit_mask & fd) &&
+		    !(sts_map[index].bit_mask & sts)) {
+			if (sts_map[index].bit_mask & sts_possible_false_pos)
+				pm_pr_dbg("%s is in D0 prior to s2idle\n",
+					  sts_map[index].name);
+			else
+				pr_err("%s is in D0 prior to s2idle\n",
+				       sts_map[index].name);
+		}
+	}
+}
+
+static void pmc_s2idle_check(void)
+{
+	struct pmc_dev *pmc = &pmc_device;
+	const struct pmc_reg_map *m = pmc->map;
+	u32 func_dis, func_dis_2;
+	u32 d3_sts_0, d3_sts_1;
+	u32 false_pos_sts_0, false_pos_sts_1;
+
+	func_dis = pmc_reg_read(pmc, PMC_FUNC_DIS);
+	func_dis_2 = pmc_reg_read(pmc, PMC_FUNC_DIS_2);
+	d3_sts_0 = pmc_reg_read(pmc, PMC_D3_STS_0);
+	d3_sts_1 = pmc_reg_read(pmc, PMC_D3_STS_1);
+
+	/*
+	 * Some blocks are not used on lower-featured versions of the SoC and
+	 * always report D0, add these to false_pos mask to log at debug level.
+	 */
+	if (m->d3_sts_1	== byt_d3_sts_1_map) {
+		/* Bay Trail */
+		false_pos_sts_0 = BIT_GBE | BIT_SATA | BIT_PCIE_PORT0 |
+			BIT_PCIE_PORT1 | BIT_PCIE_PORT2 | BIT_PCIE_PORT3 |
+			BIT_LPSS2_F5_I2C5;
+		false_pos_sts_1 = BIT_SMB | BIT_USH_SS_PHY | BIT_DFX;
+	} else {
+		/* Cherry Trail */
+		false_pos_sts_0 = BIT_GBE | BIT_SATA | BIT_LPSS2_F7_I2C7;
+		false_pos_sts_1 = BIT_SMB | BIT_STS_ISH;
+	}
+
+	pmc_dev_state_check(d3_sts_0, m->d3_sts_0, func_dis, m->func_dis, false_pos_sts_0);
+	pmc_dev_state_check(d3_sts_1, m->d3_sts_1, func_dis_2, m->func_dis_2, false_pos_sts_1);
+}
+
+static struct acpi_s2idle_dev_ops pmc_s2idle_ops = {
+	.check = pmc_s2idle_check,
+};
+
+static void pmc_s2idle_check_register(void)
+{
+	acpi_register_lps0_dev(&pmc_s2idle_ops);
+}
+#else
+static void pmc_s2idle_check_register(void) {}
+#endif
+
 static int pmc_setup_dev(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
 	struct pmc_dev *pmc = &pmc_device;
@@ -485,6 +552,7 @@ static int pmc_setup_dev(struct pci_dev *pdev, const struct pci_device_id *ent)
 		dev_warn(&pdev->dev, "platform clocks register failed: %d\n",
 			 ret);
 
+	pmc_s2idle_check_register();
 	pmc->init = true;
 	return ret;
 }