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>

drivers/Kconfig

@@ -60,6 +60,8 @@ source "drivers/sound/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/spmi/Kconfig"
+
 source "drivers/thermal/Kconfig"
 
 source "drivers/timer/Kconfig"

drivers/Makefile

@@ -54,6 +54,7 @@ obj-y += dfu/
 obj-$(CONFIG_X86) += pch/
 obj-y += rtc/
 obj-y += sound/
+obj-y += spmi/
 obj-y += timer/
 obj-y += tpm/
 obj-y += twserial/

drivers/spmi/Kconfig

@@ -0,0 +1,10 @@
+menu "SPMI support"
+
+config SPMI
+	bool "Enable SPMI bus support"
+	depends on DM
+	---help---
+	  Select this to enable to support SPMI bus.
+	  SPMI (System Power Management Interface) bus is used
+	  to connect PMIC devices on various SoCs.
+endmenu

drivers/spmi/Makefile

@@ -0,0 +1,7 @@
+#
+# (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_SPMI)  += spmi-uclass.o

drivers/spmi/spmi-uclass.c

@@ -0,0 +1,48 @@
+/*
+ * SPMI bus uclass driver
+ *
+ * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <dm/root.h>
+#include <spmi/spmi.h>
+#include <linux/ctype.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int spmi_reg_read(struct udevice *dev, int usid, int pid, int reg)
+{
+	const struct dm_spmi_ops *ops = dev_get_driver_ops(dev);
+
+	if (!ops || !ops->read)
+		return -ENOSYS;
+
+	return ops->read(dev, usid, pid, reg);
+}
+
+int spmi_reg_write(struct udevice *dev, int usid, int pid, int reg,
+		   uint8_t value)
+{
+	const struct dm_spmi_ops *ops = dev_get_driver_ops(dev);
+
+	if (!ops || !ops->write)
+		return -ENOSYS;
+
+	return ops->write(dev, usid, pid, reg, value);
+}
+
+static int spmi_post_bind(struct udevice *dev)
+{
+	return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
+}
+
+UCLASS_DRIVER(spmi) = {
+	.id		= UCLASS_SPMI,
+	.name		= "spmi",
+	.post_bind	= spmi_post_bind,
+};

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 */

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