[PATCH v3 3/6] fpga: m10bmc-sec: expose max10 flash update counts

[Russ Weight <russell.h.weight@xxxxxxxxx>]

Extend the MAX10 BMC Secure Update 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@xxxxxxxxx>
Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
---
v3:
  - Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
  - Changed "MAX10 BMC Secure Engine driver" to "MAX10 BMC Secure Update
    driver"
  - Removed wrapper functions (m10bmc_raw_*, m10bmc_sys_*). The
    underlying functions are now called directly.
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 | 33 +++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/fpga/intel-m10-bmc-secure.c b/drivers/fpga/intel-m10-bmc-secure.c
index 433af08a9507..e1fb7f7aa3e2 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 {
@@ -106,7 +107,39 @@ static int m10bmc_pr_reh(struct fpga_sec_mgr *smgr, u8 *hash,
 	return m10bmc_reh(smgr, PR_REH_ADDR, hash, size);
 }
 
+#define FLASH_COUNT_SIZE 4096	/* count stored in inverted bit vector */
+
+static int m10bmc_user_flash_count(struct fpga_sec_mgr *smgr)
+{
+	struct m10bmc_sec *sec = smgr->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 = regmap_bulk_read(sec->m10bmc->regmap, USER_FLASH_COUNT,
+			       flash_buf, FLASH_COUNT_SIZE / stride);
+	if (ret) {
+		dev_err(sec->dev,
+			"failed to read flash count: %x cnt %x: %d\n",
+			USER_FLASH_COUNT, FLASH_COUNT_SIZE / stride, 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 fpga_sec_mgr_ops m10bmc_sops = {
+	.user_flash_count = m10bmc_user_flash_count,
 	.bmc_root_entry_hash = m10bmc_bmc_reh,
 	.sr_root_entry_hash = m10bmc_sr_reh,
 	.pr_root_entry_hash = m10bmc_pr_reh,
-- 
2.17.1