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SubjectRe: [PATCH v5 3/6] fpga: m10bmc-sec: expose max10 flash update count
On Fri, Nov 13, 2020 at 04:55:56PM -0800, Russ Weight wrote:
> Extend the MAX10 BMC Secure Update driver to provide a
> sysfs file to expose the flash update count for the FPGA
> user image.
>
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> Reviewed-by: Tom Rix <trix@redhat.com>
> ---
> v5:
> - Renamed sysfs node user_flash_count to flash_count and updated the
> sysfs documentation accordingly.
> v4:
> - Moved the sysfs file for displaying the flash count from the
> FPGA Security Manager class driver to here. The
> m10bmc_user_flash_count() function is removed and the
> functionality is moved into a user_flash_count_show()
> function.
> - Added ABI documentation for the new sysfs entry
> 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
> ---
> .../testing/sysfs-driver-intel-m10-bmc-secure | 8 +++++
> drivers/fpga/intel-m10-bmc-secure.c | 34 +++++++++++++++++++
> 2 files changed, 42 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
> index 2992488b717a..73a3aba750e8 100644
> --- a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
> +++ b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
> @@ -27,3 +27,11 @@ Description: Read only. Returns the root entry hash for the BMC image
> "hash not programmed". This file is only visible if the
> underlying device supports it.
> Format: "0x%x".
> +
> +What: /sys/bus/platform/devices/n3000bmc-secure.*.auto/security/flash_count
> +Date: Oct 2020
> +KernelVersion: 5.11
> +Contact: Russ Weight <russell.h.weight@intel.com>
> +Description: Read only. Returns number of times the secure update
> + staging area has been flashed.
> + Format: "%u".
> diff --git a/drivers/fpga/intel-m10-bmc-secure.c b/drivers/fpga/intel-m10-bmc-secure.c
> index 198bc8273d6b..6ad897001086 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>
>
> struct m10bmc_sec {
> struct device *dev;
> @@ -77,7 +78,40 @@ DEVICE_ATTR_SEC_REH_RO(bmc, BMC_PROG_MAGIC, BMC_PROG_ADDR, BMC_REH_ADDR);
> DEVICE_ATTR_SEC_REH_RO(sr, SR_PROG_MAGIC, SR_PROG_ADDR, SR_REH_ADDR);
> DEVICE_ATTR_SEC_REH_RO(pr, PR_PROG_MAGIC, PR_PROG_ADDR, PR_REH_ADDR);
>
> +#define FLASH_COUNT_SIZE 4096 /* count stored as inverted bit vector */
> +
> +static ssize_t flash_count_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct m10bmc_sec *sec = dev_get_drvdata(dev);
> + unsigned int stride = regmap_get_reg_stride(sec->m10bmc->regmap);
> + unsigned int num_bits = FLASH_COUNT_SIZE * 8;
> + u8 *flash_buf;
> + int cnt, ret;

(Nit) Can you make this:

struct m10bmc_sec *sec = dev_get_drvdata(dev);
unsigned int stride, num_bits;
u8 *flash_buf;
int cnt, ret;

stride = regmap_get_reg_stride(sec->m10bmc->regmap);
num_bits = FLASH_COUNT_SIZE * 8;


> +
> + flash_buf = kmalloc(FLASH_COUNT_SIZE, GFP_KERNEL);
> + if (!flash_buf)
> + return -ENOMEM;
> +
> + ret = regmap_bulk_read(sec->m10bmc->regmap, STAGING_FLASH_COUNT,
> + flash_buf, FLASH_COUNT_SIZE / stride);
> + if (ret) {
> + dev_err(sec->dev,
> + "failed to read flash count: %x cnt %x: %d\n",
> + STAGING_FLASH_COUNT, FLASH_COUNT_SIZE / stride, ret);
> + goto exit_free;
> + }
> + cnt = num_bits - bitmap_weight((unsigned long *)flash_buf, num_bits);
> +
> +exit_free:
> + kfree(flash_buf);
> +
> + return ret ? : sysfs_emit(buf, "%u\n", cnt);
> +}
> +static DEVICE_ATTR_RO(flash_count);
> +
> static struct attribute *m10bmc_security_attrs[] = {
> + &dev_attr_flash_count.attr,
> &dev_attr_bmc_root_entry_hash.attr,
> &dev_attr_sr_root_entry_hash.attr,
> &dev_attr_pr_root_entry_hash.attr,
> --
> 2.25.1
>

Otherwise looks good to me,

- Moritz

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