On Mon, Oct 7, 2019 at 3:16 PM Cheng-Yi Chiang <cychiang@xxxxxxxxxxxx> wrote:
>
> Add an interface for other driver to query VPD value.
> This will be used for ASoC machine driver to query calibration
> data stored in VPD for smart amplifier speaker resistor
> calibration.
>
> Signed-off-by: Cheng-Yi Chiang <cychiang@xxxxxxxxxxxx>
> ---
> drivers/firmware/google/vpd.c | 16 ++++++++++++++++
> include/linux/firmware/google/google_vpd.h | 18 ++++++++++++++++++
> 2 files changed, 34 insertions(+)
> create mode 100644 include/linux/firmware/google/google_vpd.h
>
> diff --git a/drivers/firmware/google/vpd.c b/drivers/firmware/google/vpd.c
> index db0812263d46..71e9d2da63be 100644
> --- a/drivers/firmware/google/vpd.c
> +++ b/drivers/firmware/google/vpd.c
> @@ -65,6 +65,22 @@ static ssize_t vpd_attrib_read(struct file *filp, struct kobject *kobp,
> info->bin_attr.size);
> }
>
> +int vpd_attribute_read_value(bool ro, const char *key,
> + char **value, u32 value_len)
> +{
> + struct vpd_attrib_info *info;
> + struct vpd_section *sec = ro ? &ro_vpd : &rw_vpd;
> +
> + list_for_each_entry(info, &sec->attribs, list) {
> + if (strcmp(info->key, key) == 0) {
> + *value = kstrndup(info->value, value_len, GFP_KERNEL);
Value is not necessary a NULL-terminated string.
kmalloc(info->bin_attr.size) and memcpy(...) would make the most
sense.
The value_len parameter makes less sense. It seems the caller knows
the length of the value in advance.
Suggest to change the value_len to report the length of value. I.e.
*value_len = info->bin_attr.size;
Also please check the return value for memory allocation-like
functions (e.g. kstrndup, kmalloc) so that *value won't be NULL but
the function returned 0.
> + return 0;
> + }
> + }
> + return -EINVAL;
> +}
> +EXPORT_SYMBOL(vpd_attribute_read_value);
> +
> /*
> * vpd_section_check_key_name()
> *
> diff --git a/include/linux/firmware/google/google_vpd.h b/include/linux/firmware/google/google_vpd.h
> new file mode 100644
> index 000000000000..6f1160f28af8
> --- /dev/null
> +++ b/include/linux/firmware/google/google_vpd.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Google VPD interface.
> + *
> + * Copyright 2019 Google Inc.
> + */
> +
> +/* Interface for reading VPD value on Chrome platform. */
> +
> +#ifndef __GOOGLE_VPD_H
> +#define __GOOGLE_VPD_H
> +
> +#include <linux/types.h>
> +
> +int vpd_attribute_read_value(bool ro, const char *key,
> + char **value, u32 value_len);
> +
> +#endif /* __GOOGLE_VPD_H */
> --
> 2.23.0.581.g78d2f28ef7-goog
>
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