Re: [PATCH v2 2/2] nvmem: add ONIE NVMEM cells support

[Srinivas Kandagatla]

On 30/05/2020 00:04, Vadym Kochan wrote:
> ONIE is a small operating system, pre-installed on bare metal network
> switches, that provides an environment for automated provisioning.
>
> This system requires that NVMEM (EEPROM) device holds various system
> information (mac address, platform name, etc) in a special TLV layout.
>
> The driver registers ONIE TLV attributes as NVMEM cells which can be
> accessed by other platform driver. Also it allows to use
> of_get_mac_address() to retrieve mac address for the netdev.
>
> Signed-off-by: Vadym Kochan <vadym.kochan@xxxxxxxxxxx>
> ---
>   drivers/nvmem/Kconfig      |   9 +
>   drivers/nvmem/Makefile     |   3 +
>   drivers/nvmem/onie-cells.c | 332 +++++++++++++++++++++++++++++++++++++

Is there a reason why Device tree bindings are missing for this driver?



>   3 files changed, 344 insertions(+)
>   create mode 100644 drivers/nvmem/onie-cells.c
>
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> index d7b7f6d688e7..dd9298487992 100644
> --- a/drivers/nvmem/Kconfig
> +++ b/drivers/nvmem/Kconfig
> @@ -273,4 +273,13 @@ config SPRD_EFUSE
>   	  This driver can also be built as a module. If so, the module
>   	  will be called nvmem-sprd-efuse.
>   
> +config NVMEM_ONIE_CELLS
> +	tristate "ONIE TLV cells support"
> +	help
> +	  This is a driver to provide cells from ONIE TLV structure stored
> +	  on NVME device.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called nvmem-onie-cells.
> +
>   endif
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index a7c377218341..2199784a489f 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -55,3 +55,6 @@ obj-$(CONFIG_NVMEM_ZYNQMP)	+= nvmem_zynqmp_nvmem.o
>   nvmem_zynqmp_nvmem-y		:= zynqmp_nvmem.o
>   obj-$(CONFIG_SPRD_EFUSE)	+= nvmem_sprd_efuse.o
>   nvmem_sprd_efuse-y		:= sprd-efuse.o
> +
> +obj-$(CONFIG_NVMEM_ONIE_CELLS)	+= nvmem-onie-cells.o
> +nvmem-onie-cells-y		:= onie-cells.o
> diff --git a/drivers/nvmem/onie-cells.c b/drivers/nvmem/onie-cells.c
> new file mode 100644
> index 000000000000..1e8b4b8d1c0d
> --- /dev/null
> +++ b/drivers/nvmem/onie-cells.c
> @@ -0,0 +1,332 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * ONIE NVMEM cells provider
> + *
> + * Author: Vadym Kochan <vadym.kochan@xxxxxxxxxxx>
> + */
> +
> +#define ONIE_NVMEM_DRVNAME	"onie-nvmem-cells"
> +
> +#define pr_fmt(fmt) ONIE_NVMEM_DRVNAME ": " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/nvmem-consumer.h>
> +#include <linux/nvmem-provider.h>
> +
> +#define ONIE_NVMEM_TLV_MAX_LEN	2048
> +
> +#define ONIE_NVMEM_HDR_ID	"TlvInfo"
> +

...

> +
> +static int onie_nvmem_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct nvmem_cell_info *cells;
> +	struct onie_nvmem_attr *attr;
> +	struct nvmem_device *nvmem;
> +	struct onie_nvmem *onie;
> +	unsigned int ncells = 0;
> +	int err;
> +
> +	nvmem = of_nvmem_device_get(np, NULL);
> +	if (IS_ERR(nvmem))
> +		return PTR_ERR(nvmem);
> +
TBH, this looks completely incorrect way to do this and misuse of nvmem 
consumer interface.

Ideally nvmem provider driver should populate "cells" in struct 
nvmem_config after decoding them and then register nvmem provider.

That should just work!


--srini


> +	onie = kmalloc(sizeof(*onie), GFP_KERNEL);
> +	if (!onie) {
> +		err = -ENOMEM;
> +		goto err_nvmem_alloc;
> +	}
> +
> +	INIT_LIST_HEAD(&onie->attrs);
> +	onie->attr_count = 0;
> +	onie->nvmem = nvmem;
> +
> +	err = onie_nvmem_decode(onie);
> +	if (err)
> +		goto err_nvmem_decode;
> +
> +	if (!onie->attr_count) {
> +		pr_err("%s: has no ONIE attributes\n", nvmem_dev_name(nvmem));
> +		err = -EINVAL;
> +		goto err_no_attrs;
> +	}
> +
> +	cells = kmalloc_array(onie->attr_count, sizeof(*cells), GFP_KERNEL);
> +	if (!cells) {
> +		err = -ENOMEM;
> +		goto err_cells_alloc;
> +	}
> +
> +	onie->cell_lookup = kmalloc_array(onie->attr_count,
> +					  sizeof(struct nvmem_cell_lookup),
> +					  GFP_KERNEL);
> +	if (!onie->cell_lookup) {
> +		err = -ENOMEM;
> +		goto err_lookup_alloc;
> +	}
> +
> +	list_for_each_entry(attr, &onie->attrs, head) {
> +		struct nvmem_cell_lookup *lookup;
> +		struct nvmem_cell_info *cell;
> +
> +		cell = &cells[ncells];
> +
> +		lookup = &onie->cell_lookup[ncells];
> +		lookup->con_id = NULL;
> +
> +		cell->offset = attr->offset;
> +		cell->name = attr->name;
> +		cell->bytes = attr->len;
> +		cell->bit_offset = 0;
> +		cell->nbits = 0;
> +
> +		lookup->nvmem_name = nvmem_dev_name(onie->nvmem);
> +		lookup->dev_id = dev_name(dev);
> +		lookup->cell_name = cell->name;
> +		lookup->con_id = cell->name;
> +
> +		ncells++;
> +	}
> +
> +	onie->cell_tbl.nvmem_name = nvmem_dev_name(onie->nvmem);
> +	onie->cell_tbl.ncells = ncells;
> +	onie->cell_tbl.cells = cells;
> +
> +	nvmem_add_cell_table(&onie->cell_tbl);
> +	nvmem_add_cell_lookups(onie->cell_lookup, ncells);
> +
> +	dev_set_drvdata(dev, onie);
> +
> +	onie_nvmem_attrs_free(onie);
> +
> +	nvmem_device_put(nvmem);
> +
> +	return 0;
> +
> +err_lookup_alloc:
> +	kfree(onie->cell_tbl.cells);
> +err_cells_alloc:
> +	onie_nvmem_attrs_free(onie);
> +err_no_attrs:
> +err_nvmem_decode:
> +	kfree(onie);
> +err_nvmem_alloc:
> +	nvmem_device_put(nvmem);
> +
> +	return err;
> +}
> +