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Date: Wed, 2 Mar 2016 13:59:38 +0000
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Andrey Smirnov <andrew.smirnov@...il.com>,
linux-kernel@...r.kernel.org
Cc: maxime.ripard@...e-electrons.com
Subject: Re: [RESEND RFC 3/3] nvmem: Add 'nvmem-composite' driver
On 01/03/16 16:59, Andrey Smirnov wrote:
> Add 'nvmem-composite' driver which allows to combine multiple chunks of
> various NVMEM cells into a single continuous NVMEM device.
My plan on this feature was add support inside the nvmem_cell_get
itself, this makes the nvmem bindings more inline with bindings like
pinctrl.
Also I still want to keep nvmem simple as it can.
DT would look something like this.
nvmem-provider-a {
cell_a {
reg = <0 2>;
};
};
nvmem-provider-b {
cell_b: cell_c {
reg = <0 1>;
};
};
nvmem-provider-c {
cell_c: cell_c {
reg = <3 2>;
}
};
a-node {
nvmem-cells = <&cell_a &cell_b &cell_c>
nvmem-cell-names = "some-data";
};
thanks,
srini
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
> ---
> .../devicetree/bindings/nvmem/composite.txt | 44 ++++
> drivers/nvmem/Makefile | 1 +
> drivers/nvmem/composite.c | 225 +++++++++++++++++++++
> 3 files changed, 270 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/nvmem/composite.txt
> create mode 100644 drivers/nvmem/composite.c
>
> diff --git a/Documentation/devicetree/bindings/nvmem/composite.txt b/Documentation/devicetree/bindings/nvmem/composite.txt
> new file mode 100644
> index 0000000..e24cf4b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/composite.txt
> @@ -0,0 +1,44 @@
> += NVMEM cell compositor =
> +
> +This binding is designed to provide a way for a developer to combine
> +portions of other NVMEM cell and acces that data as a signle NVMEM
> +cell using NVMEM consumer API.
> +
> +Required properties:
> +- compatible: should be "nvmem-composite"
> +- layout: specifies which sources comprise data in nvmem device
> + format is "<nvmem-cell-phandle offset size>"
> +
> += Data cells =
> +Are child nodes of nvmem-composite, bindings of which as described in
> +bindings/nvmem/nvmem.txt
> +
> +Example:
> +
> + composite-nvmem {
> + compatible = "nvmem-composite";
> + layout = <&another_cell_a 0 2
> + &another_cell_b 0 1
> + &another_cell_c 3 2>;
> +
> + cell1: cell@0 {
> + reg = <0 5>;
> + };
> + }
> +
> +the result of reading variable cell1 would be:
> +
> +[a[0] a[1] b[0] c[3] c[4]],
> +
> +where a[i], b[i], c[i], represnet i-th bytes of NVMEM cells
> +another_cell_a, another_cell_b and another_cell_c respectively
> +
> += Data consumers =
> +Are device nodes which consume nvmem data cells.
> +
> +Example:
> +
> + a-node {
> + nvmem-cells = <&cell1>;
> + nvmem-cell-names = "some-data";
> + };
> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
> index 1a1adba..49c0eca 100644
> --- a/drivers/nvmem/Makefile
> +++ b/drivers/nvmem/Makefile
> @@ -19,3 +19,4 @@ nvmem_sunxi_sid-y := sunxi_sid.o
> obj-$(CONFIG_NVMEM_VF610_OCOTP) += nvmem-vf610-ocotp.o
> nvmem-vf610-ocotp-y := vf610-ocotp.o
> obj-y += blob.o
> +obj-y += composite.o
> diff --git a/drivers/nvmem/composite.c b/drivers/nvmem/composite.c
> new file mode 100644
> index 0000000..cf01590
> --- /dev/null
> +++ b/drivers/nvmem/composite.c
> @@ -0,0 +1,225 @@
> +#define DEBUG 1
> +
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/nvmem-consumer.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +struct nvmem_composite {
> + struct device *dev;
> + struct list_head layout;
> + size_t layout_size;
> +};
> +
> +struct nvmem_composite_item {
> + struct nvmem_cell *cell;
> + unsigned int idx, start, end, size;
> + struct list_head node;
> +};
> +
> +static struct nvmem_composite_item *
> +nvmem_composite_find_first(struct nvmem_composite *ncomp,
> + unsigned int offset)
> +{
> + struct nvmem_composite_item *first;
> + list_for_each_entry(first, &ncomp->layout, node) {
> + /*
> + * Skip all of the irrelevant items that end before our offset
> + */
> + if (first->end > offset)
> + return first;
> + }
> +
> + return NULL;
> +}
> +
> +static int nvmem_composite_read(void *context,
> + const void *reg, size_t reg_size,
> + void *val, size_t val_size)
> +{
> + struct nvmem_composite *ncomp = context;
> + const unsigned int offset = *(u32 *)reg;
> + void *dst = val;
> + size_t residue = val_size;
> + struct nvmem_composite_item *item, *first;
> + uint8_t *data;
> + unsigned int size, chunk, ii;
> +
> +
> + first = item = nvmem_composite_find_first(ncomp, offset);
> + if (!first) {
> + dev_dbg(ncomp->dev, "Invalid offset\n");
> + return -EINVAL;
> + }
> +
> + list_for_each_entry_from(item, &ncomp->layout, node) {
> + /*
> + * If our first read is not located on item boundary
> + * we have to introduce artificial offset
> + */
> + ii = (item == first) ? offset - first->start : 0;
> +
> + data = nvmem_cell_read(item->cell, &size);
> + if (IS_ERR(data)) {
> + dev_dbg(ncomp->dev, "Failed to read nvmem cell\n");
> + return PTR_ERR(data);
> + }
> +
> + chunk = min(residue, item->size - ii);
> + memcpy(dst, &data[item->idx + ii], chunk);
> + kfree(data);
> +
> + dst += chunk;
> + residue -= chunk;
> + }
> +
> + return (residue) ? -EINVAL : 0;
> +}
> +
> +static int nvmem_composite_write(void *context, const void *data,
> + size_t count)
> +{
> + return -ENOTSUPP;
> +}
> +
> +static const struct regmap_bus nvmem_composite_regmap_bus = {
> + .write = nvmem_composite_write,
> + .read = nvmem_composite_read,
> +};
> +
> +static int nvmem_composite_validate_dt(struct device_node *np)
> +{
> + /* FIXME */
> + return 0;
> +}
> +
> +static int nvmem_composite_probe(struct platform_device *pdev)
> +{
> + int i, ret;
> + unsigned int start = 0;
> + unsigned int len;
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + struct nvmem_device *nvmem;
> + struct nvmem_composite *ncomp;
> + struct regmap *map;
> + struct nvmem_composite_item *item;
> + struct nvmem_config nv_cnf = {0};
> + struct regmap_config rm_cnf = {0};
> + const __be32 *addr;
> + unsigned int item_count;
> +
> + ret = nvmem_composite_validate_dt(np);
> + if (ret < 0) {
> + dev_dbg(dev, "Device validation failed\n");
> + return ret;
> + }
> +
> + ncomp = devm_kzalloc(dev, sizeof(*ncomp), GFP_KERNEL);
> + INIT_LIST_HEAD(&ncomp->layout);
> + ncomp->dev = dev;
> +
> + addr = of_get_property(np, "layout", &len);
> + item_count = len / (3 * sizeof(__be32));
> +
> + for (i = 0; i < item_count; i++) {
> + struct device_node *cell_np;
> + uint32_t phandle;
> +
> + item = devm_kzalloc(dev, sizeof(*item), GFP_KERNEL);
> +
> + phandle = be32_to_cpup(addr++);
> + cell_np = of_find_node_by_phandle(phandle);
> + if (!cell_np) {
> + dev_dbg(dev,
> + "Couldn't find nvmem cell by its phandle\n");
> + return -ENOENT;
> + }
> +
> + item->cell = of_nvmem_cell_from_device_node(cell_np);
> + if (IS_ERR(item->cell)) {
> + dev_dbg(dev,
> + "Failed to instantiate nvmem cell from "
> + "a device tree node\n");
> + ret = PTR_ERR(item->cell);
> + goto unwind;
> + }
> +
> + item->start = start;
> + item->idx = be32_to_cpup(addr++);
> + item->size = be32_to_cpup(addr++);
> + item->end = item->size - 1;
> + ncomp->layout_size += item->size;
> + start += item->size;
> +
> + list_add_tail(&item->node, &ncomp->layout);
> + }
> +
> + rm_cnf.reg_bits = 32;
> + rm_cnf.val_bits = 8;
> + rm_cnf.reg_stride = 1;
> + rm_cnf.name = "nvmem-composite";
> + rm_cnf.max_register = ncomp->layout_size - 1;
> +
> + map = devm_regmap_init(dev,
> + &nvmem_composite_regmap_bus,
> + ncomp,
> + &rm_cnf);
> + if (IS_ERR(map)) {
> + dev_dbg(dev, "Failed to initilize regmap\n");
> + return PTR_ERR(map);
> + }
> +
> + nv_cnf.name = "nvmem-composite";
> + nv_cnf.read_only = true;
> + nv_cnf.dev = dev;
> +
> + nvmem = nvmem_register(&nv_cnf);
> + if (IS_ERR(nvmem)) {
> + dev_dbg(dev, "Failed to register 'nvmem' device\n");
> + return PTR_ERR(nvmem);
> + }
> +
> + platform_set_drvdata(pdev, nvmem);
> + return 0;
> +unwind:
> + /* FIXME */
> + return ret;
> +}
> +
> +static int nvmem_composite_remove(struct platform_device *pdev)
> +{
> + struct nvmem_device *nvmem = platform_get_drvdata(pdev);
> +
> + /*
> + FIXME free allocated nvmem cells
> + */
> + return nvmem_unregister(nvmem);
> +}
> +
> +
> +static const struct of_device_id nvmem_composite_dt_ids[] = {
> + { .compatible = "nvmem-composite", },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, nvmem_composite_dt_ids);
> +
> +static struct platform_driver nvmem_composite_driver = {
> + .probe = nvmem_composite_probe,
> + .remove = nvmem_composite_remove,
> + .driver = {
> + .name = "nvmem-composite",
> + .of_match_table = nvmem_composite_dt_ids,
> + },
> +};
> +module_platform_driver(nvmem_composite_driver);
> +
> +MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@...il.com>");
> +MODULE_DESCRIPTION("FIXME");
> +MODULE_LICENSE("GPL v2");
>
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