[PATCH v2 3/6] fpga: m10bmc-sec: expose max10 flash update counts

[Russ Weight <russell.h.weight@intel.com>]

Extend the MAX10 BMC Security Engine driver to provide a
handler to expose the flash update count for the FPGA user
image in sysfs.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
---
v2:
  - Renamed get_qspi_flash_count() to m10bmc_user_flash_count()
  - Minor code cleanup per review comments
  - Added m10bmc_ prefix to functions in m10bmc_iops structure
---
 drivers/fpga/intel-m10-bmc-secure.c | 31 +++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/fpga/intel-m10-bmc-secure.c b/drivers/fpga/intel-m10-bmc-secure.c
index df8ebda9a9cb..da61cfda3c50 100644
--- a/drivers/fpga/intel-m10-bmc-secure.c
+++ b/drivers/fpga/intel-m10-bmc-secure.c
@@ -11,6 +11,7 @@
 #include <linux/mfd/intel-m10-bmc.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
 #include <linux/vmalloc.h>
 
 struct m10bmc_sec {
@@ -105,7 +106,37 @@ static int m10bmc_pr_root_entry_hash(struct ifpga_sec_mgr *imgr,
 	return m10bmc_root_entry_hash(imgr, PR_REH_ADDR, hash, size);
 }
 
+#define FLASH_COUNT_SIZE 4096	/* count stored in inverted bit vector */
+
+static int m10bmc_user_flash_count(struct ifpga_sec_mgr *imgr)
+{
+	struct m10bmc_sec *sec = imgr->priv;
+	unsigned int stride = regmap_get_reg_stride(sec->m10bmc->regmap);
+	unsigned int num_bits = FLASH_COUNT_SIZE * 8;
+	u8 *flash_buf;
+	int ret;
+
+	flash_buf = kmalloc(FLASH_COUNT_SIZE, GFP_KERNEL);
+	if (!flash_buf)
+		return -ENOMEM;
+
+	ret = m10bmc_raw_bulk_read(sec->m10bmc, USER_FLASH_COUNT, flash_buf,
+				   FLASH_COUNT_SIZE / stride);
+	if (ret) {
+		dev_err(sec->dev, "%s failed to read %d\n", __func__, ret);
+		goto exit_free;
+	}
+
+	ret = num_bits - bitmap_weight((unsigned long *)flash_buf, num_bits);
+
+exit_free:
+	kfree(flash_buf);
+
+	return ret;
+}
+
 static const struct ifpga_sec_mgr_ops m10bmc_iops = {
+	.user_flash_count = m10bmc_user_flash_count,
 	.bmc_root_entry_hash = m10bmc_bmc_root_entry_hash,
 	.sr_root_entry_hash = m10bmc_sr_root_entry_hash,
 	.pr_root_entry_hash = m10bmc_pr_root_entry_hash,
-- 
2.17.1