platform/x86: intel_pmc_core: Quirk to ignore XTAL shutdown

On some platforms such as HP Elite-x2-1013-g3, the platform BIOS
enforces XTAL to remain off before S0ix state can be achieved. This may
not be optimum when we want to enable use cases like Low Power Audio,
Wake on Voice etc which always need 24mhz clock.

This introduces a new quirk to allow S0ix entry when all other
conditions except for XTAL clock are good on a given platform. The extra
power consumed by XTAL clock is about 2mw but it saves much more
platform power compared to the system that remains in just PC10.

Link: https://bit.ly/2UmnrFf
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201579
Tested-by: "David E. Box" <david.e.box@linux.intel.com>
Reported-and-tested-by: russianneuromancer <russianneuromancer@ya.ru>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
index b9f34e492a24..f2c621b55f49 100644
--- a/drivers/platform/x86/intel_pmc_core.c
+++ b/drivers/platform/x86/intel_pmc_core.c
@@ -15,6 +15,7 @@
 #include <linux/bitfield.h>
 #include <linux/debugfs.h>
 #include <linux/delay.h>
+#include <linux/dmi.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -151,6 +152,7 @@ static const struct pmc_reg_map spt_reg_map = {
 	.pm_cfg_offset = SPT_PMC_PM_CFG_OFFSET,
 	.pm_read_disable_bit = SPT_PMC_READ_DISABLE_BIT,
 	.ltr_ignore_max = SPT_NUM_IP_IGN_ALLOWED,
+	.pm_vric1_offset = SPT_PMC_VRIC1_OFFSET,
 };
 
 /* Cannonlake: PGD PFET Enable Ack Status Register(s) bitmap */
@@ -821,6 +823,37 @@ static const struct pci_device_id pmc_pci_ids[] = {
 	{ 0, },
 };
 
+/*
+ * This quirk can be used on those platforms where
+ * the platform BIOS enforces 24Mhx Crystal to shutdown
+ * before PMC can assert SLP_S0#.
+ */
+int quirk_xtal_ignore(const struct dmi_system_id *id)
+{
+	struct pmc_dev *pmcdev = &pmc;
+	u32 value;
+
+	value = pmc_core_reg_read(pmcdev, pmcdev->map->pm_vric1_offset);
+	/* 24MHz Crystal Shutdown Qualification Disable */
+	value |= SPT_PMC_VRIC1_XTALSDQDIS;
+	/* Low Voltage Mode Enable */
+	value &= ~SPT_PMC_VRIC1_SLPS0LVEN;
+	pmc_core_reg_write(pmcdev, pmcdev->map->pm_vric1_offset, value);
+	return 0;
+}
+
+static const struct dmi_system_id pmc_core_dmi_table[]  = {
+	{
+	.callback = quirk_xtal_ignore,
+	.ident = "HP Elite x2 1013 G3",
+	.matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "HP"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "HP Elite x2 1013 G3"),
+		},
+	},
+	{}
+};
+
 static int __init pmc_core_probe(void)
 {
 	struct pmc_dev *pmcdev = &pmc;
@@ -862,6 +895,7 @@ static int __init pmc_core_probe(void)
 		return err;
 	}
 
+	dmi_check_system(pmc_core_dmi_table);
 	pr_info(" initialized\n");
 	return 0;
 }