drivers: Add SPMI bus uclass

Qualcom processors use proprietary bus to talk with PMIC devices -
SPMI (System Power Management Interface).
On wiring level it is similar to I2C, but on protocol level, it's
multi-master and has simple autodetection capabilities.
This commit adds simple uclass that provides bus read/write interface.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

2 files changed, 47 insertions, 0 deletions

diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index 37c4176..cbf9b2c 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -66,6 +66,7 @@ enum uclass_id {
 	UCLASS_RTC,		/* Real time clock device */
 	UCLASS_SERIAL,		/* Serial UART */
 	UCLASS_SPI,		/* SPI bus */
+	UCLASS_SPMI,		/* System Power Management Interface bus */
 	UCLASS_SPI_FLASH,	/* SPI flash */
 	UCLASS_SPI_GENERIC,	/* Generic SPI flash target */
 	UCLASS_SYSCON,		/* System configuration device */
diff --git a/include/spmi/spmi.h b/include/spmi/spmi.h
new file mode 100644
index 0000000..3242e6b
--- /dev/null
+++ b/include/spmi/spmi.h
@@ -0,0 +1,46 @@
+#ifndef _SPMI_SPMI_H
+#define _SPMI_SPMI_H
+
+/**
+ * struct dm_spmi_ops - SPMI device I/O interface
+ *
+ * Should be implemented by UCLASS_SPMI device drivers. The standard
+ * device operations provides the I/O interface for it's childs.
+ *
+ * @read:      read register 'reg' of slave 'usid' and peripheral 'pid'
+ * @write:     write register 'reg' of slave 'usid' and peripheral 'pid'
+ *
+ * Each register is 8-bit, both read and write can return negative values
+ * on error.
+ */
+struct dm_spmi_ops {
+	int (*read)(struct udevice *dev, int usid, int pid, int reg);
+	int (*write)(struct udevice *dev, int usid, int pid, int reg,
+		     uint8_t value);
+};
+
+/**
+ * spmi_reg_read() - read a register from specific slave/peripheral
+ *
+ * @dev:	SPMI bus to read
+ * @usid	SlaveID
+ * @pid		Peripheral ID
+ * @reg:	Register to read
+ * @return value read on success or negative value of errno.
+ */
+int spmi_reg_read(struct udevice *dev, int usid, int pid, int reg);
+
+/**
+ * spmi_reg_write() - write a register of specific slave/peripheral
+ *
+ * @dev:	SPMI bus to write
+ * @usid	SlaveID
+ * @pid		Peripheral ID
+ * @reg:	Register to write
+ * @value:	Value to write
+ * @return 0 on success or negative value of errno.
+ */
+int spmi_reg_write(struct udevice *dev, int usid, int pid, int reg,
+		   uint8_t value);
+
+#endif