linux-kernel - Re: [PATCH v1 03/12] fpga: expose max10 flash update counts in sysfs

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Date:   Sat, 5 Sep 2020 13:39:50 -0700
From:   Tom Rix <trix@...hat.com>
To:     Russ Weight <russell.h.weight@...el.com>, mdf@...nel.org,
        lee.jones@...aro.org, linux-fpga@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     lgoncalv@...hat.com, yilun.xu@...el.com, hao.wu@...el.com,
        matthew.gerlach@...el.com
Subject: Re: [PATCH v1 03/12] fpga: expose max10 flash update counts in sysfs


On 9/4/20 4:52 PM, Russ Weight wrote:
> Extend the MAX10 BMC Security Engine driver to provide a
> handler to expose the flash update count for the FPGA user
> image.
>
> Signed-off-by: Russ Weight <russell.h.weight@...el.com>
> Reviewed-by: Wu Hao <hao.wu@...el.com>
> ---
>  drivers/fpga/intel-m10-bmc-secure.c | 32 +++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/drivers/fpga/intel-m10-bmc-secure.c b/drivers/fpga/intel-m10-bmc-secure.c
> index 1f86bfb694b4..b824790e43aa 100644
> --- a/drivers/fpga/intel-m10-bmc-secure.c
> +++ b/drivers/fpga/intel-m10-bmc-secure.c
> @@ -10,6 +10,7 @@
>  #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 {
> @@ -99,7 +100,38 @@ SYSFS_GET_REH(bmc, BMC_REH_ADDR)
>  SYSFS_GET_REH(sr, SR_REH_ADDR)
>  SYSFS_GET_REH(pr, PR_REH_ADDR)
>  
> +#define FLASH_COUNT_SIZE 4096
This seems too high at most it should be 64.
> +#define USER_FLASH_COUNT 0x17ffb000
Why shouldn't this be in intel-m10-bmc.h ?
> +
> +static int get_qspi_flash_count(struct ifpga_sec_mgr *imgr)

what does 'qspi' mean ?

unless there are going to be several *flash_count's consider

removing this substring.

> +{
> +	struct m10bmc_sec *sec = imgr->priv;
> +	unsigned int stride = regmap_get_reg_stride(sec->m10bmc->regmap);
> +	unsigned int cnt, 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;
> +	}
> +
> +	cnt = num_bits - bitmap_weight((unsigned long *)flash_buf, num_bits);
Simplify ret = num_bits...
> +
> +exit_free:
> +	kfree(flash_buf);
> +
> +	return ret ? : cnt;

Then simplify

return ret;

Tom

> +}
> +
>  static const struct ifpga_sec_mgr_ops m10bmc_iops = {
> +	.user_flash_count = get_qspi_flash_count,
>  	.bmc_root_entry_hash = get_bmc_root_entry_hash,
>  	.sr_root_entry_hash = get_sr_root_entry_hash,
>  	.pr_root_entry_hash = get_pr_root_entry_hash,