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    Subject[PATCH v2 11/16] nvmem: add support for cell info
    Date
    From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

    Add new structs and routines allowing users to define nvmem cells from
    machine code. This global list of entries is parsed when a provider
    is registered and cells are associated with the relevant nvmem_device
    struct.

    A possible improvement for the future is to allow users to register
    cell tables after the nvmem provider has been registered by updating
    the cell list at each call to nvmem_(add|del)_cell_table().

    Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
    ---
    MAINTAINERS | 1 +
    drivers/nvmem/core.c | 97 ++++++++++++++++++++++++++++++++++-
    include/linux/nvmem-machine.h | 41 +++++++++++++++
    3 files changed, 138 insertions(+), 1 deletion(-)
    create mode 100644 include/linux/nvmem-machine.h

    diff --git a/MAINTAINERS b/MAINTAINERS
    index 9ad052aeac39..a520924bf0a9 100644
    --- a/MAINTAINERS
    +++ b/MAINTAINERS
    @@ -10391,6 +10391,7 @@ F: drivers/nvmem/
    F: Documentation/devicetree/bindings/nvmem/
    F: Documentation/ABI/stable/sysfs-bus-nvmem
    F: include/linux/nvmem-consumer.h
    +F: include/linux/nvmem-machine.h
    F: include/linux/nvmem-provider.h

    NXP SGTL5000 DRIVER
    diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
    index 17307015905a..854baa0559a1 100644
    --- a/drivers/nvmem/core.c
    +++ b/drivers/nvmem/core.c
    @@ -21,6 +21,7 @@
    #include <linux/init.h>
    #include <linux/module.h>
    #include <linux/nvmem-consumer.h>
    +#include <linux/nvmem-machine.h>
    #include <linux/nvmem-provider.h>
    #include <linux/of.h>
    #include <linux/slab.h>
    @@ -58,6 +59,9 @@ struct nvmem_cell {
    static DEFINE_MUTEX(nvmem_mutex);
    static DEFINE_IDA(nvmem_ida);

    +static DEFINE_MUTEX(nvmem_cell_mutex);
    +static LIST_HEAD(nvmem_cell_tables);
    +
    static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);

    #ifdef CONFIG_DEBUG_LOCK_ALLOC
    @@ -341,6 +345,66 @@ static int nvmem_setup_compat(struct nvmem_device *nvmem,
    return 0;
    }

    +static struct nvmem_cell *
    +nvmem_cell_from_cell_info(struct nvmem_device *nvmem,
    + struct nvmem_cell_info *info)
    +{
    + struct nvmem_cell *cell;
    +
    + cell = kzalloc(sizeof(*cell), GFP_KERNEL);
    + if (!cell)
    + return ERR_PTR(-ENOMEM);
    +
    + cell->nvmem = nvmem;
    + cell->offset = info->offset;
    + cell->bytes = info->bytes;
    + cell->name = info->name;
    + cell->bit_offset = info->bit_offset;
    + cell->nbits = info->nbits;
    +
    + if (cell->nbits)
    + cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
    + BITS_PER_BYTE);
    +
    + if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
    + dev_err(&nvmem->dev,
    + "cell %s unaligned to nvmem stride %d\n",
    + cell->name, nvmem->stride);
    + kfree(cell);
    + return ERR_PTR(-EINVAL);
    + }
    +
    + return cell;
    +}
    +
    +static int nvmem_add_cells_from_list(struct nvmem_device *nvmem)
    +{
    + struct nvmem_cell_table *table;
    + struct nvmem_cell_info *info;
    + struct nvmem_cell *cell;
    + int rval = 0, i;
    +
    + mutex_lock(&nvmem_cell_mutex);
    + list_for_each_entry(table, &nvmem_cell_tables, node) {
    + if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
    + for (i = 0; i < table->ncells; i++) {
    + info = &table->cells[i];
    + cell = nvmem_cell_from_cell_info(nvmem, info);
    + if (IS_ERR(cell)) {
    + rval = PTR_ERR(cell);
    + goto out;
    + }
    +
    + nvmem_cell_add(cell);
    + }
    + }
    + }
    +
    +out:
    + mutex_unlock(&nvmem_cell_mutex);
    + return rval;
    +}
    +
    /**
    * nvmem_register_notifier() - Register a notifier block for nvmem events.
    *
    @@ -447,13 +511,18 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
    }

    INIT_LIST_HEAD(&nvmem->cells);
    + rval = nvmem_add_cells_from_list(nvmem);
    + if (rval)
    + goto err_teardown_compat;

    rval = blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
    if (rval)
    - goto err_teardown_compat;
    + goto err_remove_cells;

    return nvmem;

    +err_remove_cells:
    + nvmem_device_remove_all_cells(nvmem);
    err_teardown_compat:
    if (config->compat)
    device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
    @@ -1179,6 +1248,32 @@ int nvmem_device_write(struct nvmem_device *nvmem,
    }
    EXPORT_SYMBOL_GPL(nvmem_device_write);

    +/**
    + * nvmem_add_cell_table() - register a table of cell info entries
    + *
    + * @table: table of cell info entries
    + */
    +void nvmem_add_cell_table(struct nvmem_cell_table *table)
    +{
    + mutex_lock(&nvmem_cell_mutex);
    + list_add_tail(&table->node, &nvmem_cell_tables);
    + mutex_unlock(&nvmem_cell_mutex);
    +}
    +EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
    +
    +/**
    + * nvmem_del_cell_table() - remove a previously registered cell info table
    + *
    + * @table: table of cell info entries
    + */
    +void nvmem_del_cell_table(struct nvmem_cell_table *table)
    +{
    + mutex_lock(&nvmem_cell_mutex);
    + list_del(&table->node);
    + mutex_unlock(&nvmem_cell_mutex);
    +}
    +EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
    +
    /**
    * nvmem_dev_name() - Get the name of a given nvmem device.
    *
    diff --git a/include/linux/nvmem-machine.h b/include/linux/nvmem-machine.h
    new file mode 100644
    index 000000000000..1e199dfaacab
    --- /dev/null
    +++ b/include/linux/nvmem-machine.h
    @@ -0,0 +1,41 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +/*
    + * nvmem framework machine code bindings
    + *
    + * Copyright (C) 2018 Bartosz Golaszewski <bgolaszewski@baylibre.com>
    + */
    +
    +#ifndef _LINUX_NVMEM_MACHINE_H
    +#define _LINUX_NVMEM_MACHINE_H
    +
    +#include <linux/nvmem-provider.h>
    +#include <linux/list.h>
    +
    +struct nvmem_cell_info {
    + const char *name;
    + unsigned int offset;
    + unsigned int bytes;
    + unsigned int bit_offset;
    + unsigned int nbits;
    +};
    +
    +struct nvmem_cell_table {
    + const char *nvmem_name;
    + struct nvmem_cell_info *cells;
    + size_t ncells;
    + struct list_head node;
    +};
    +
    +#if IS_ENABLED(CONFIG_NVMEM)
    +
    +void nvmem_add_cell_table(struct nvmem_cell_table *table);
    +void nvmem_del_cell_table(struct nvmem_cell_table *table);
    +
    +#else /* CONFIG_NVMEM */
    +
    +static inline void nvmem_add_cell_table(struct nvmem_cell_table *table) {}
    +static inline void nvmem_del_cell_table(struct nvmem_cell_table *table) {}
    +
    +#endif /* CONFIG_NVMEM */
    +
    +#endif /* ifndef _LINUX_NVMEM_MACHINE_H */
    --
    2.18.0
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