[PATCH v2 02/10] platform/x86/intel/pmt: Add register access callbacks

["Michael J. Ruhl" <michael.j.ruhl@intel.com>]

Some HW does not have direct MMIO access to PMT control and data
features.

Augment the current callback infrastructure (data access) to allow
a registered driver to customize read/write access to the control
paths for PMT usage.

Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
---
 drivers/platform/x86/intel/pmt/crashlog.c | 39 +++++++++++++++++++++--
 include/linux/intel_vsec.h                | 14 +++++++-
 2 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/intel/pmt/crashlog.c b/drivers/platform/x86/intel/pmt/crashlog.c
index f936daf99e4d..5923ad7abbd9 100644
--- a/drivers/platform/x86/intel/pmt/crashlog.c
+++ b/drivers/platform/x86/intel/pmt/crashlog.c
@@ -129,7 +129,19 @@ static void pmt_crashlog_rmw(struct crashlog_entry *crashlog, u32 bit, bool set)
 {
 	const struct crashlog_control *control = &crashlog->info->control;
 	struct intel_pmt_entry *entry = &crashlog->entry;
-	u32 reg = readl(entry->disc_table + control->offset);
+	u32 guid = entry->header.guid;
+	u32 reg;
+	int err;
+
+	if (entry->cb && entry->cb->read_reg) {
+		err = entry->cb->read_reg(entry->dev, guid, &reg, control->offset);
+		if (err) {
+			pr_err("%s: failed to read reg: %d\n", __func__, err);
+			return;
+		}
+	} else {
+		reg = readl(entry->disc_table + control->offset);
+	}
 
 	reg &= ~control->trigger_mask;
 
@@ -138,14 +150,35 @@ static void pmt_crashlog_rmw(struct crashlog_entry *crashlog, u32 bit, bool set)
 	else
 		reg &= ~bit;
 
-	writel(reg, entry->disc_table + control->offset);
+	if (entry->cb && entry->cb->write_reg) {
+		err = entry->cb->write_reg(entry->dev, guid, reg, control->offset);
+		if (err) {
+			pr_err("%s: failed to write reg: %d\n", __func__, err);
+			return;
+		}
+	} else {
+		writel(reg, entry->disc_table + control->offset);
+	}
 }
 
 /* Read the status register and see if the specified @bit is set */
 static bool pmt_crashlog_rc(struct crashlog_entry *crashlog, u32 bit)
 {
 	const struct crashlog_status *status = &crashlog->info->status;
-	u32 reg = readl(crashlog->entry.disc_table + status->offset);
+	struct intel_pmt_entry *entry = &crashlog->entry;
+	u32 guid = entry->header.guid;
+	u32 reg;
+	int err;
+
+	if (entry->cb && entry->cb->read_reg) {
+		err = entry->cb->read_reg(entry->dev, guid, &reg, status->offset);
+		if (err) {
+			pr_err("%s: failed to read reg: %d\n", __func__, err);
+			return false;
+		}
+	} else {
+		reg = readl(crashlog->entry.disc_table + status->offset);
+	}
 
 	return !!(reg & bit);
 }
diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
index 843cda8f8644..917d9397a993 100644
--- a/include/linux/intel_vsec.h
+++ b/include/linux/intel_vsec.h
@@ -90,13 +90,25 @@ enum intel_vsec_quirks {
  * @read_telem: when specified, called by client driver to access PMT
  * data (instead of direct copy).
  * * dev:   device reference for the callback's use
- * * guid:  ID of data to acccss
+ * * guid:  ID of data to access
  * * data:  buffer for the data to be copied
  * * off:   offset into the requested buffer
  * * count: size of buffer
+ * @read_reg: when specified called by client driver to read PMT state
+ * * dev:      device reference for the callback's use
+ * * guid:     ID of data to access
+ * * reg_data: register data
+ * * offset:   offset of register to read
+ * @write_reg: when specified called by client driver to write PMT state
+ * * dev:      device reference for the callback's use
+ * * guid:     ID of data to access
+ * * reg_data: register data
+ * * offset:   offset of register to write
  */
 struct pmt_callbacks {
 	int (*read_telem)(struct device *dev, u32 guid, u64 *data, loff_t off, u32 count);
+	int (*read_reg)(struct device *dev, u32 guid, u32 *reg_data, u32 offset);
+	int (*write_reg)(struct device *dev, u32 guid, u32 reg_data, u32 offset);
 };
 
 struct vsec_feature_dependency {
-- 
2.43.0