[PATCH 4/6] regmap: add MMIO bus support

From: Stephen Warren
Date: Wed Apr 04 2012 - 17:48:45 EST

From: Stephen Warren <swarren@xxxxxxxxxx>

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@xxxxxxxxxx>
---
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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