[PATCH v6 04/18] 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 | 46 +++++++++++++++++++++--
 include/linux/intel_vsec.h                | 14 ++++++-
 2 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/intel/pmt/crashlog.c b/drivers/platform/x86/intel/pmt/crashlog.c
index b6540f3a9a17..912b61c334a6 100644
--- a/drivers/platform/x86/intel/pmt/crashlog.c
+++ b/drivers/platform/x86/intel/pmt/crashlog.c
@@ -11,10 +11,12 @@
 #include <linux/auxiliary_bus.h>
 #include <linux/cleanup.h>
 #include <linux/intel_vsec.h>
+#include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/pci.h>
+#include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/overflow.h>
@@ -124,12 +126,36 @@ struct pmt_crashlog_priv {
  * I/O
  */
 
+static int pmt_crashlog_read_reg(struct intel_pmt_entry *entry, u32 *reg, u32 offset)
+{
+	int ret;
+
+	*reg = 0;
+
+	if (entry->cb && entry->cb->read_reg) {
+		ret = entry->cb->read_reg(entry->dev, entry->header.guid, reg, offset);
+		if (ret) {
+			pr_err_ratelimited("failed to read reg: %d\n", ret);
+			return ret;
+		}
+	} else {
+		*reg = readl(entry->disc_table + offset);
+	}
+
+	return 0;
+}
+
 /* Read, modify, write the control register, setting or clearing @bit based on @set */
 static int 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 reg;
+	int ret;
+
+	ret = pmt_crashlog_read_reg(entry, &reg, control->offset);
+	if (ret)
+		return ret;
 
 	reg &= ~control->trigger_mask;
 
@@ -138,7 +164,15 @@ static int 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) {
+		ret = entry->cb->write_reg(entry->dev, entry->header.guid, reg, control->offset);
+		if (ret) {
+			pr_err_ratelimited("failed to write reg: %d\n", ret);
+			return ret;
+		}
+	} else {
+		writel(reg, entry->disc_table + control->offset);
+	}
 
 	return 0;
 }
@@ -147,7 +181,13 @@ static int pmt_crashlog_rmw(struct crashlog_entry *crashlog, u32 bit, bool set)
 static int pmt_crashlog_rc(struct crashlog_entry *crashlog, u32 bit, bool *state)
 {
 	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 reg;
+	int ret;
+
+	ret = pmt_crashlog_read_reg(entry, &reg, status->offset);
+	if (ret)
+		return ret;
 
 	*state = !!(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