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    Subject[PATCH 4/6] regmap: add MMIO bus support
    Date
    From: Stephen Warren <swarren@nvidia.com>

    This is a basic memory-mapped-IO bus for regmap. It has the following
    features and limitations:

    * Registers themselves may be 8, 16, 32, or 64-bit. 64-bit is only
    supported on 64-bit platforms.
    * Register offsets are limited to precisely 32-bit.
    * IO is performed using readl/writel, with no provision for using the
    __raw_readl or readl_relaxed variants.

    Signed-off-by: Stephen Warren <swarren@nvidia.com>
    ---
    drivers/base/regmap/Kconfig | 3 +
    drivers/base/regmap/Makefile | 1 +
    drivers/base/regmap/regmap-mmio.c | 217 +++++++++++++++++++++++++++++++++++++
    include/linux/regmap.h | 6 +
    4 files changed, 227 insertions(+), 0 deletions(-)
    create mode 100644 drivers/base/regmap/regmap-mmio.c

    diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
    index 0f6c7fb..9ef0a53 100644
    --- a/drivers/base/regmap/Kconfig
    +++ b/drivers/base/regmap/Kconfig
    @@ -14,5 +14,8 @@ config REGMAP_I2C
    config REGMAP_SPI
    tristate

    +config REGMAP_MMIO
    + tristate
    +
    config REGMAP_IRQ
    bool
    diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
    index defd579..5e75d1b 100644
    --- a/drivers/base/regmap/Makefile
    +++ b/drivers/base/regmap/Makefile
    @@ -3,4 +3,5 @@ obj-$(CONFIG_REGMAP) += regcache-rbtree.o regcache-lzo.o
    obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
    obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o
    obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
    +obj-$(CONFIG_REGMAP_MMIO) += regmap-mmio.o
    obj-$(CONFIG_REGMAP_IRQ) += regmap-irq.o
    diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
    new file mode 100644
    index 0000000..1a7b5ee
    --- /dev/null
    +++ b/drivers/base/regmap/regmap-mmio.c
    @@ -0,0 +1,217 @@
    +/*
    + * Register map access API - MMIO support
    + *
    + * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
    + *
    + * This program is free software; you can redistribute it and/or modify it
    + * under the terms and conditions of the GNU General Public License,
    + * version 2, as published by the Free Software Foundation.
    + *
    + * This program is distributed in the hope it will be useful, but WITHOUT
    + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
    + * more details.
    + *
    + * You should have received a copy of the GNU General Public License
    + * along with this program. If not, see <http://www.gnu.org/licenses/>.
    + */
    +
    +#include <linux/err.h>
    +#include <linux/init.h>
    +#include <linux/io.h>
    +#include <linux/module.h>
    +#include <linux/regmap.h>
    +#include <linux/slab.h>
    +
    +struct regmap_mmio_context {
    + void __iomem *regs;
    + unsigned val_bytes;
    +};
    +
    +static int regmap_mmio_gather_write(void *context,
    + const void *reg, size_t reg_size,
    + const void *val, size_t val_size)
    +{
    + struct regmap_mmio_context *ctx = context;
    + u32 offset;
    +
    + if (reg_size != 4)
    + return -EIO;
    + if (val_size % ctx->val_bytes)
    + return -EIO;
    +
    + offset = be32_to_cpup(reg);
    +
    + while (val_size) {
    + switch (ctx->val_bytes) {
    + case 1:
    + writeb(*(u8 *)val, ctx->regs + offset);
    + break;
    + case 2:
    + writew(be16_to_cpup(val), ctx->regs + offset);
    + break;
    + case 4:
    + writel(be32_to_cpup(val), ctx->regs + offset);
    + break;
    +#ifdef CONFIG_64BIT
    + case 8:
    + writeq(be64_to_cpup(val), ctx->regs + offset);
    + break;
    +#endif
    + default:
    + /* Should be caught by regmap_mmio_check_config */
    + return -EIO;
    + }
    + val_size -= ctx->val_bytes;
    + val += ctx->val_bytes;
    + offset += ctx->val_bytes;
    + }
    +
    + return 0;
    +}
    +
    +static int regmap_mmio_write(void *context, const void *data, size_t count)
    +{
    + if (count < 4)
    + return -EIO;
    + return regmap_mmio_gather_write(context, data, 4, data + 4, count - 4);
    +}
    +
    +static int regmap_mmio_read(void *context,
    + const void *reg, size_t reg_size,
    + void *val, size_t val_size)
    +{
    + struct regmap_mmio_context *ctx = context;
    + u32 offset;
    +
    + if (reg_size != 4)
    + return -EIO;
    + if (val_size % ctx->val_bytes)
    + return -EIO;
    +
    + offset = be32_to_cpup(reg);
    +
    + while (val_size) {
    + switch (ctx->val_bytes) {
    + case 1:
    + *(u8 *)val = readb(ctx->regs + offset);
    + break;
    + case 2:
    + *(u16 *)val = cpu_to_be16(readw(ctx->regs + offset));
    + break;
    + case 4:
    + *(u32 *)val = cpu_to_be32(readl(ctx->regs + offset));
    + break;
    +#ifdef CONFIG_64BIT
    + case 8:
    + *(u64 *)val = cpu_to_be32(readq(ctx->regs + offset));
    + break;
    +#endif
    + default:
    + /* Should be caught by regmap_mmio_check_config */
    + return -EIO;
    + }
    + val_size -= ctx->val_bytes;
    + val += ctx->val_bytes;
    + offset += ctx->val_bytes;
    + }
    +
    + return 0;
    +}
    +
    +static void regmap_mmio_free_context(void *context)
    +{
    + kfree(context);
    +}
    +
    +static struct regmap_bus regmap_mmio = {
    + .fast_io = true,
    + .write = regmap_mmio_write,
    + .gather_write = regmap_mmio_gather_write,
    + .read = regmap_mmio_read,
    + .free_context = regmap_mmio_free_context,
    +};
    +
    +struct regmap_mmio_context *regmap_mmio_gen_context(void __iomem *regs,
    + const struct regmap_config *config)
    +{
    + struct regmap_mmio_context *ctx;
    +
    + if (config->reg_bits != 32)
    + return ERR_PTR(-EINVAL);
    +
    + if (config->pad_bits)
    + return ERR_PTR(-EINVAL);
    +
    + switch (config->val_bits) {
    + case 8:
    + case 16:
    + case 32:
    +#ifdef CONFIG_64BIT
    + case 64:
    +#endif
    + break;
    + default:
    + return ERR_PTR(-EINVAL);
    + }
    +
    + ctx = kzalloc(GFP_KERNEL, sizeof(*ctx));
    + if (!ctx)
    + return ERR_PTR(-ENOMEM);
    +
    + ctx->regs = regs;
    + ctx->val_bytes = config->val_bits / 8;
    +
    + return ctx;
    +}
    +
    +/**
    + * regmap_init_mmio(): Initialise register map
    + *
    + * @dev: Device that will be interacted with
    + * @regs: Pointer to memory-mapped IO region
    + * @config: Configuration for register map
    + *
    + * The return value will be an ERR_PTR() on error or a valid pointer to
    + * a struct regmap.
    + */
    +struct regmap *regmap_init_mmio(struct device *dev,
    + void __iomem *regs,
    + const struct regmap_config *config)
    +{
    + struct regmap_mmio_context *ctx;
    +
    + ctx = regmap_mmio_gen_context(regs, config);
    + if (IS_ERR(ctx))
    + return ERR_CAST(ctx);
    +
    + return regmap_init(dev, &regmap_mmio, ctx, config);
    +}
    +EXPORT_SYMBOL_GPL(regmap_init_mmio);
    +
    +/**
    + * devm_regmap_init_mmio(): Initialise managed register map
    + *
    + * @dev: Device that will be interacted with
    + * @regs: Pointer to memory-mapped IO region
    + * @config: Configuration for register map
    + *
    + * The return value will be an ERR_PTR() on error or a valid pointer
    + * to a struct regmap. The regmap will be automatically freed by the
    + * device management code.
    + */
    +struct regmap *devm_regmap_init_mmio(struct device *dev,
    + void __iomem *regs,
    + const struct regmap_config *config)
    +{
    + struct regmap_mmio_context *ctx;
    +
    + ctx = regmap_mmio_gen_context(regs, config);
    + if (IS_ERR(ctx))
    + return ERR_CAST(ctx);
    +
    + return devm_regmap_init(dev, &regmap_mmio, ctx, config);
    +}
    +EXPORT_SYMBOL_GPL(devm_regmap_init_mmio);
    +
    +MODULE_LICENSE("GPL v2");
    diff --git a/include/linux/regmap.h b/include/linux/regmap.h
    index 3ff16f0..680ddd7 100644
    --- a/include/linux/regmap.h
    +++ b/include/linux/regmap.h
    @@ -142,6 +142,9 @@ struct regmap *regmap_init_i2c(struct i2c_client *i2c,
    const struct regmap_config *config);
    struct regmap *regmap_init_spi(struct spi_device *dev,
    const struct regmap_config *config);
    +struct regmap *regmap_init_mmio(struct device *dev,
    + void __iomem *regs,
    + const struct regmap_config *config);

    struct regmap *devm_regmap_init(struct device *dev,
    const struct regmap_bus *bus,
    @@ -151,6 +154,9 @@ struct regmap *devm_regmap_init_i2c(struct i2c_client *i2c,
    const struct regmap_config *config);
    struct regmap *devm_regmap_init_spi(struct spi_device *dev,
    const struct regmap_config *config);
    +struct regmap *devm_regmap_init_mmio(struct device *dev,
    + void __iomem *regs,
    + const struct regmap_config *config);

    void regmap_exit(struct regmap *map);
    int regmap_reinit_cache(struct regmap *map,
    --
    1.7.0.4


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