platform/x86: intel_pmc_core: Add option to set/clear LPM mode

By default the Low Power Mode (LPM or sub-state) status registers will
latch condition status on every entry into Package C10. This is
configurable in the PMC to allow latching on any achievable sub-state. Add
a debugfs file to support this.

Also add the option to clear the status registers to 0. Clearing the status
registers before testing removes ambiguity around when the current values
were set.

The new file, latch_lpm_mode, looks like this:

	[c10] S0i2.0 S0i3.0 S0i2.1 S0i3.1 S0i3.2 clear

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210417031252.3020837-8-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 112 insertions, 0 deletions

diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
index 56823f17e113..5240eefe8e6e 100644
--- a/drivers/platform/x86/intel_pmc_core.c
+++ b/drivers/platform/x86/intel_pmc_core.c
@@ -586,6 +586,7 @@ static const struct pmc_reg_map tgl_reg_map = {
 	.ltr_ignore_max = TGL_NUM_IP_IGN_ALLOWED,
 	.lpm_num_maps = TGL_LPM_NUM_MAPS,
 	.lpm_res_counter_step_x2 = TGL_PMC_LPM_RES_COUNTER_STEP_X2,
+	.lpm_sts_latch_en_offset = TGL_LPM_STS_LATCH_EN_OFFSET,
 	.lpm_en_offset = TGL_LPM_EN_OFFSET,
 	.lpm_priority_offset = TGL_LPM_PRI_OFFSET,
 	.lpm_residency_offset = TGL_LPM_RESIDENCY_OFFSET,
@@ -1321,6 +1322,114 @@ static int pmc_core_substate_req_regs_show(struct seq_file *s, void *unused)
 }
 DEFINE_SHOW_ATTRIBUTE(pmc_core_substate_req_regs);
 
+static int pmc_core_lpm_latch_mode_show(struct seq_file *s, void *unused)
+{
+	struct pmc_dev *pmcdev = s->private;
+	bool c10;
+	u32 reg;
+	int idx, mode;
+
+	reg = pmc_core_reg_read(pmcdev, pmcdev->map->lpm_sts_latch_en_offset);
+	if (reg & LPM_STS_LATCH_MODE) {
+		seq_puts(s, "c10");
+		c10 = false;
+	} else {
+		seq_puts(s, "[c10]");
+		c10 = true;
+	}
+
+	pmc_for_each_mode(idx, mode, pmcdev) {
+		if ((BIT(mode) & reg) && !c10)
+			seq_printf(s, " [%s]", pmc_lpm_modes[mode]);
+		else
+			seq_printf(s, " %s", pmc_lpm_modes[mode]);
+	}
+
+	seq_puts(s, " clear\n");
+
+	return 0;
+}
+
+static ssize_t pmc_core_lpm_latch_mode_write(struct file *file,
+					     const char __user *userbuf,
+					     size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct pmc_dev *pmcdev = s->private;
+	bool clear = false, c10 = false;
+	unsigned char buf[8];
+	size_t ret;
+	int idx, m, mode;
+	u32 reg;
+
+	if (count > sizeof(buf) - 1)
+		return -EINVAL;
+
+	ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, userbuf, count);
+	if (ret < 0)
+		return ret;
+
+	buf[count] = '\0';
+
+	/*
+	 * Allowed strings are:
+	 *	Any enabled substate, e.g. 'S0i2.0'
+	 *	'c10'
+	 *	'clear'
+	 */
+	mode = sysfs_match_string(pmc_lpm_modes, buf);
+
+	/* Check string matches enabled mode */
+	pmc_for_each_mode(idx, m, pmcdev)
+		if (mode == m)
+			break;
+
+	if (mode != m || mode < 0) {
+		if (sysfs_streq(buf, "clear"))
+			clear = true;
+		else if (sysfs_streq(buf, "c10"))
+			c10 = true;
+		else
+			return -EINVAL;
+	}
+
+	if (clear) {
+		mutex_lock(&pmcdev->lock);
+
+		reg = pmc_core_reg_read(pmcdev, pmcdev->map->etr3_offset);
+		reg |= ETR3_CLEAR_LPM_EVENTS;
+		pmc_core_reg_write(pmcdev, pmcdev->map->etr3_offset, reg);
+
+		mutex_unlock(&pmcdev->lock);
+
+		return count;
+	}
+
+	if (c10) {
+		mutex_lock(&pmcdev->lock);
+
+		reg = pmc_core_reg_read(pmcdev, pmcdev->map->lpm_sts_latch_en_offset);
+		reg &= ~LPM_STS_LATCH_MODE;
+		pmc_core_reg_write(pmcdev, pmcdev->map->lpm_sts_latch_en_offset, reg);
+
+		mutex_unlock(&pmcdev->lock);
+
+		return count;
+	}
+
+	/*
+	 * For LPM mode latching we set the latch enable bit and selected mode
+	 * and clear everything else.
+	 */
+	reg = LPM_STS_LATCH_MODE | BIT(mode);
+	mutex_lock(&pmcdev->lock);
+	pmc_core_reg_write(pmcdev, pmcdev->map->lpm_sts_latch_en_offset, reg);
+	mutex_unlock(&pmcdev->lock);
+
+	return count;
+}
+DEFINE_PMC_CORE_ATTR_WRITE(pmc_core_lpm_latch_mode);
+
 static int pmc_core_pkgc_show(struct seq_file *s, void *unused)
 {
 	struct pmc_dev *pmcdev = s->private;
@@ -1439,6 +1548,9 @@ static void pmc_core_dbgfs_register(struct pmc_dev *pmcdev)
 		debugfs_create_file("substate_live_status_registers", 0444,
 				    pmcdev->dbgfs_dir, pmcdev,
 				    &pmc_core_substate_l_sts_regs_fops);
+		debugfs_create_file("lpm_latch_mode", 0644,
+				    pmcdev->dbgfs_dir, pmcdev,
+				    &pmc_core_lpm_latch_mode_fops);
 	}
 
 	if (pmcdev->lpm_req_regs) {