regmap: spmi: support base and extended register spaces

SPMI states that a slave may contain two register spaces, the Base
register space is a 5-bit byte-addressable space accessed via the
Register Read/Write and Register Zero Write command sequences, and the
Extended register space: a 16-bit byte-addressable space accessed via
the Extended Read/Write and Extended Read/Write Long command sequences.

Provide support for accessing both of these spaces, taking advantage of
the more bandwidth-efficient commands ('Register 0 Write' vs 'Register
Write', and 'Extended Register Read/Write' vs 'Extended Register
Read/Write Long') when possible.

Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
Acked-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 205 insertions, 35 deletions

diff --git a/drivers/base/regmap/regmap-spmi.c b/drivers/base/regmap/regmap-spmi.c
index ac2391013db1..d7026dc33388 100644
--- a/drivers/base/regmap/regmap-spmi.c
+++ b/drivers/base/regmap/regmap-spmi.c
@@ -22,69 +22,235 @@
 #include <linux/module.h>
 #include <linux/init.h>
 
-static int regmap_spmi_read(void *context,
-                            const void *reg, size_t reg_size,
-                            void *val, size_t val_size)
+static int regmap_spmi_base_read(void *context,
+                                 const void *reg, size_t reg_size,
+                                 void *val, size_t val_size)
 {
+        u8 addr = *(u8 *)reg;
+        int err = 0;
+
+        BUG_ON(reg_size != 1);
+
+        while (val_size-- && !err)
+                err = spmi_register_read(context, addr++, val++);
+
+        return err;
+}
+
+static int regmap_spmi_base_gather_write(void *context,
+                                         const void *reg, size_t reg_size,
+                                         const void *val, size_t val_size)
+{
+        const u8 *data = val;
+        u8 addr = *(u8 *)reg;
+        int err = 0;
+
+        BUG_ON(reg_size != 1);
+
+        /*
+         * SPMI defines a more bandwidth-efficient 'Register 0 Write' sequence,
+         * use it when possible.
+         */
+        if (addr == 0 && val_size) {
+                err = spmi_register_zero_write(context, *data);
+                if (err)
+                        goto err_out;
+
+                data++;
+                addr++;
+                val_size--;
+        }
+
+        while (val_size) {
+                err = spmi_register_write(context, addr, *data);
+                if (err)
+                        goto err_out;
+
+                data++;
+                addr++;
+                val_size--;
+        }
+
+err_out:
+        return err;
+}
+
+static int regmap_spmi_base_write(void *context, const void *data,
+                                  size_t count)
+{
+        BUG_ON(count < 1);
+        return regmap_spmi_base_gather_write(context, data, 1, data + 1,
+                                             count - 1);
+}
+
+static struct regmap_bus regmap_spmi_base = {
+        .read                           = regmap_spmi_base_read,
+        .write                          = regmap_spmi_base_write,
+        .gather_write                   = regmap_spmi_base_gather_write,
+        .reg_format_endian_default      = REGMAP_ENDIAN_NATIVE,
+        .val_format_endian_default      = REGMAP_ENDIAN_NATIVE,
+};
+
+/**
+ * regmap_init_spmi_base(): Create regmap for the Base register space
+ * @sdev:       SPMI device that will be interacted with
+ * @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_spmi_base(struct spmi_device *sdev,
+                                     const struct regmap_config *config)
+{
+        return regmap_init(&sdev->dev, &regmap_spmi_base, sdev, config);
+}
+EXPORT_SYMBOL_GPL(regmap_init_spmi_base);
+
+/**
+ * devm_regmap_init_spmi_base(): Create managed regmap for Base register space
+ * @sdev:       SPMI device that will be interacted with
+ * @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_spmi_base(struct spmi_device *sdev,
+                                          const struct regmap_config *config)
+{
+        return devm_regmap_init(&sdev->dev, &regmap_spmi_base, sdev, config);
+}
+EXPORT_SYMBOL_GPL(devm_regmap_init_spmi_base);
+
+static int regmap_spmi_ext_read(void *context,
+                                const void *reg, size_t reg_size,
+                                void *val, size_t val_size)
+{
+        int err = 0;
+        size_t len;
+        u16 addr;
+
         BUG_ON(reg_size != 2);
-        return spmi_ext_register_readl(context, *(u16 *)reg,
-                                       val, val_size);
+
+        addr = *(u16 *)reg;
+
+        /*
+         * Split accesses into two to take advantage of the more
+         * bandwidth-efficient 'Extended Register Read' command when possible
+         */
+        while (addr <= 0xFF && val_size) {
+                len = min_t(size_t, val_size, 16);
+
+                err = spmi_ext_register_read(context, addr, val, len);
+                if (err)
+                        goto err_out;
+
+                addr += len;
+                val += len;
+                val_size -= len;
+        }
+
+        while (val_size) {
+                len = min_t(size_t, val_size, 8);
+
+                err = spmi_ext_register_readl(context, addr, val, val_size);
+                if (err)
+                        goto err_out;
+
+                addr += len;
+                val += len;
+                val_size -= len;
+        }
+
+err_out:
+        return err;
 }
 
-static int regmap_spmi_gather_write(void *context,
-                                    const void *reg, size_t reg_size,
-                                    const void *val, size_t val_size)
+static int regmap_spmi_ext_gather_write(void *context,
+                                        const void *reg, size_t reg_size,
+                                        const void *val, size_t val_size)
 {
+        int err = 0;
+        size_t len;
+        u16 addr;
+
         BUG_ON(reg_size != 2);
-        return spmi_ext_register_writel(context, *(u16 *)reg, val, val_size);
+
+        addr = *(u16 *)reg;
+
+        while (addr <= 0xFF && val_size) {
+                len = min_t(size_t, val_size, 16);
+
+                err = spmi_ext_register_write(context, addr, val, len);
+                if (err)
+                        goto err_out;
+
+                addr += len;
+                val += len;
+                val_size -= len;
+        }
+
+        while (val_size) {
+                len = min_t(size_t, val_size, 8);
+
+                err = spmi_ext_register_writel(context, addr, val, len);
+                if (err)
+                        goto err_out;
+
+                addr += len;
+                val += len;
+                val_size -= len;
+        }
+
+err_out:
+        return err;
 }
 
-static int regmap_spmi_write(void *context, const void *data,
-                             size_t count)
+static int regmap_spmi_ext_write(void *context, const void *data,
+                                 size_t count)
 {
         BUG_ON(count < 2);
-        return regmap_spmi_gather_write(context, data, 2, data + 2, count - 2);
+        return regmap_spmi_ext_gather_write(context, data, 2, data + 2,
+                                            count - 2);
 }
 
-static struct regmap_bus regmap_spmi = {
-        .read                           = regmap_spmi_read,
-        .write                          = regmap_spmi_write,
-        .gather_write                   = regmap_spmi_gather_write,
+static struct regmap_bus regmap_spmi_ext = {
+        .read                           = regmap_spmi_ext_read,
+        .write                          = regmap_spmi_ext_write,
+        .gather_write                   = regmap_spmi_ext_gather_write,
         .reg_format_endian_default      = REGMAP_ENDIAN_NATIVE,
         .val_format_endian_default      = REGMAP_ENDIAN_NATIVE,
 };
 
 /**
- * regmap_init_spmi(): Initialize register map
- *
- * @sdev: Device that will be interacted with
- * @config: Configuration for register map
+ * regmap_init_spmi_ext(): Create regmap for Ext register space
+ * @sdev:       Device that will be interacted with
+ * @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_spmi(struct spmi_device *sdev,
-                                const struct regmap_config *config)
+struct regmap *regmap_init_spmi_ext(struct spmi_device *sdev,
+                                    const struct regmap_config *config)
 {
-        return regmap_init(&sdev->dev, &regmap_spmi, sdev, config);
+        return regmap_init(&sdev->dev, &regmap_spmi_ext, sdev, config);
 }
-EXPORT_SYMBOL_GPL(regmap_init_spmi);
+EXPORT_SYMBOL_GPL(regmap_init_spmi_ext);
 
 /**
- * devm_regmap_init_spmi(): Initialise managed register map
- *
- * @sdev: Device that will be interacted with
- * @config: Configuration for register map
+ * devm_regmap_init_spmi_ext(): Create managed regmap for Ext register space
+ * @sdev:       SPMI device that will be interacted with
+ * @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_spmi(struct spmi_device *sdev,
+struct regmap *devm_regmap_init_spmi_ext(struct spmi_device *sdev,
                                      const struct regmap_config *config)
 {
-        return devm_regmap_init(&sdev->dev, &regmap_spmi, sdev, config);
+        return devm_regmap_init(&sdev->dev, &regmap_spmi_ext, sdev, config);
 }
-EXPORT_SYMBOL_GPL(devm_regmap_init_spmi);
+EXPORT_SYMBOL_GPL(devm_regmap_init_spmi_ext);
 
 MODULE_LICENSE("GPL");
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 4149f1a9b003..8cc73ac6f888 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -321,8 +321,10 @@ 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_spmi(struct spmi_device *dev,
-                               const struct regmap_config *config);
+struct regmap *regmap_init_spmi_base(struct spmi_device *dev,
+                                     const struct regmap_config *config);
+struct regmap *regmap_init_spmi_ext(struct spmi_device *dev,
+                                    const struct regmap_config *config);
 struct regmap *regmap_init_mmio_clk(struct device *dev, const char *clk_id,
                                     void __iomem *regs,
                                     const struct regmap_config *config);
@@ -335,8 +337,10 @@ 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_spmi(struct spmi_device *dev,
-                                     const struct regmap_config *config);
+struct regmap *devm_regmap_init_spmi_base(struct spmi_device *dev,
+                                          const struct regmap_config *config);
+struct regmap *devm_regmap_init_spmi_ext(struct spmi_device *dev,
+                                         const struct regmap_config *config);
 struct regmap *devm_regmap_init_mmio_clk(struct device *dev, const char *clk_id,
                                          void __iomem *regs,
                                          const struct regmap_config *config);