Merge tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

Pull ARM SoC driver updates from Olof Johansson:
 "As we've enabled multiplatform kernels on ARM, and greatly done away
  with the contents under arch/arm/mach-*, there's still need for
  SoC-related drivers to go somewhere.

  Many of them go in through other driver trees, but we still have
  drivers/soc to hold some of the "doesn't fit anywhere" lowlevel code
  that might be shared between ARM and ARM64 (or just in general makes
  sense to not have under the architecture directory).

  This branch contains mostly such code:

   - Drivers for qualcomm SoCs for SMEM, SMD and SMD-RPM, used to
     communicate with power management blocks on these SoCs for use by
     clock, regulator and bus frequency drivers.

   - Allwinner Reduced Serial Bus driver, again used to communicate with
     PMICs.

   - Drivers for ARM's SCPI (System Control Processor).  Not to be
     confused with PSCI (Power State Coordination Interface).  SCPI is
     used to communicate with the assistant embedded cores doing power
     management, and we have yet to see how many of them will implement
     this for their hardware vs abstracting in other ways (or not at all
     like in the past).

   - To make confusion between SCPI and PSCI more likely, this release
     also includes an update of PSCI to interface version 1.0.

   - Rockchip support for power domains.

   - A driver to talk to the firmware on Raspberry Pi"

* tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (57 commits)
  soc: qcom: smd-rpm: Correct size of outgoing message
  bus: sunxi-rsb: Add driver for Allwinner Reduced Serial Bus
  bus: sunxi-rsb: Add Allwinner Reduced Serial Bus (RSB) controller bindings
  ARM: bcm2835: add mutual inclusion protection
  drivers: psci: make PSCI 1.0 functions initialization version dependent
  dt-bindings: Correct paths in Rockchip power domains binding document
  soc: rockchip: power-domain: don't try to print the clock name in error case
  soc: qcom/smem: add HWSPINLOCK dependency
  clk: berlin: add cpuclk
  ARM: berlin: dts: add CLKID_CPU for BG2Q
  ARM: bcm2835: Add the Raspberry Pi firmware driver
  soc: qcom: smem: Move RPM message ram out of smem DT node
  soc: qcom: smd-rpm: Correct the active vs sleep state flagging
  soc: qcom: smd: delete unneeded of_node_put
  firmware: qcom-scm: build for correct architecture level
  soc: qcom: smd: Correct SMEM items for upper channels
  qcom-scm: add missing prototype for qcom_scm_is_available()
  qcom-scm: fix endianess issue in __qcom_scm_is_call_available
  soc: qcom: smd: Reject send of too big packets
  soc: qcom: smd: Handle big endian CPUs
  ...

3 files changed, 795 insertions, 0 deletions

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 0ebca8ba7bc4..116b363b7987 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -120,6 +120,17 @@ config SIMPLE_PM_BUS
 	  Controller (BSC, sometimes called "LBSC within Bus Bridge", or
 	  "External Bus Interface") as found on several Renesas ARM SoCs.
 
+config SUNXI_RSB
+	tristate "Allwinner sunXi Reduced Serial Bus Driver"
+	  default MACH_SUN8I || MACH_SUN9I
+	  depends on ARCH_SUNXI
+	  select REGMAP
+	  help
+	  Say y here to enable support for Allwinner's Reduced Serial Bus
+	  (RSB) support. This controller is responsible for communicating
+	  with various RSB based devices, such as AXP223, AXP8XX PMICs,
+	  and AC100/AC200 ICs.
+
 config VEXPRESS_CONFIG
 	bool "Versatile Express configuration bus"
 	default y if ARCH_VEXPRESS
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 790e7b933fb2..fcb9f9794a1f 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -15,5 +15,6 @@ obj-$(CONFIG_MVEBU_MBUS) 	+= mvebu-mbus.o
 obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
 
 obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
+obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
new file mode 100644
index 000000000000..846bc29c157d
--- /dev/null
+++ b/drivers/bus/sunxi-rsb.c
@@ -0,0 +1,783 @@
+/*
+ * RSB (Reduced Serial Bus) driver.
+ *
+ * Author: Chen-Yu Tsai <wens@csie.org>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ *
+ * The RSB controller looks like an SMBus controller which only supports
+ * byte and word data transfers. But, it differs from standard SMBus
+ * protocol on several aspects:
+ * - it uses addresses set at runtime to address slaves. Runtime addresses
+ *   are sent to slaves using their 12bit hardware addresses. Up to 15
+ *   runtime addresses are available.
+ * - it adds a parity bit every 8bits of data and address for read and
+ *   write accesses; this replaces the ack bit
+ * - only one read access is required to read a byte (instead of a write
+ *   followed by a read access in standard SMBus protocol)
+ * - there's no Ack bit after each read access
+ *
+ * This means this bus cannot be used to interface with standard SMBus
+ * devices. Devices known to support this interface include the AXP223,
+ * AXP809, and AXP806 PMICs, and the AC100 audio codec, all from X-Powers.
+ *
+ * A description of the operation and wire protocol can be found in the
+ * RSB section of Allwinner's A80 user manual, which can be found at
+ *
+ *     https://github.com/allwinner-zh/documents/tree/master/A80
+ *
+ * This document is officially released by Allwinner.
+ *
+ * This driver is based on i2c-sun6i-p2wi.c, the P2WI bus driver.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/clk/clk-conf.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/sunxi-rsb.h>
+#include <linux/types.h>
+
+/* RSB registers */
+#define RSB_CTRL	0x0	/* Global control */
+#define RSB_CCR		0x4	/* Clock control */
+#define RSB_INTE	0x8	/* Interrupt controls */
+#define RSB_INTS	0xc	/* Interrupt status */
+#define RSB_ADDR	0x10	/* Address to send with read/write command */
+#define RSB_DATA	0x1c	/* Data to read/write */
+#define RSB_LCR		0x24	/* Line control */
+#define RSB_DMCR	0x28	/* Device mode (init) control */
+#define RSB_CMD		0x2c	/* RSB Command */
+#define RSB_DAR		0x30	/* Device address / runtime address */
+
+/* CTRL fields */
+#define RSB_CTRL_START_TRANS		BIT(7)
+#define RSB_CTRL_ABORT_TRANS		BIT(6)
+#define RSB_CTRL_GLOBAL_INT_ENB		BIT(1)
+#define RSB_CTRL_SOFT_RST		BIT(0)
+
+/* CLK CTRL fields */
+#define RSB_CCR_SDA_OUT_DELAY(v)	(((v) & 0x7) << 8)
+#define RSB_CCR_MAX_CLK_DIV		0xff
+#define RSB_CCR_CLK_DIV(v)		((v) & RSB_CCR_MAX_CLK_DIV)
+
+/* STATUS fields */
+#define RSB_INTS_TRANS_ERR_ACK		BIT(16)
+#define RSB_INTS_TRANS_ERR_DATA_BIT(v)	(((v) >> 8) & 0xf)
+#define RSB_INTS_TRANS_ERR_DATA		GENMASK(11, 8)
+#define RSB_INTS_LOAD_BSY		BIT(2)
+#define RSB_INTS_TRANS_ERR		BIT(1)
+#define RSB_INTS_TRANS_OVER		BIT(0)
+
+/* LINE CTRL fields*/
+#define RSB_LCR_SCL_STATE		BIT(5)
+#define RSB_LCR_SDA_STATE		BIT(4)
+#define RSB_LCR_SCL_CTL			BIT(3)
+#define RSB_LCR_SCL_CTL_EN		BIT(2)
+#define RSB_LCR_SDA_CTL			BIT(1)
+#define RSB_LCR_SDA_CTL_EN		BIT(0)
+
+/* DEVICE MODE CTRL field values */
+#define RSB_DMCR_DEVICE_START		BIT(31)
+#define RSB_DMCR_MODE_DATA		(0x7c << 16)
+#define RSB_DMCR_MODE_REG		(0x3e << 8)
+#define RSB_DMCR_DEV_ADDR		0x00
+
+/* CMD values */
+#define RSB_CMD_RD8			0x8b
+#define RSB_CMD_RD16			0x9c
+#define RSB_CMD_RD32			0xa6
+#define RSB_CMD_WR8			0x4e
+#define RSB_CMD_WR16			0x59
+#define RSB_CMD_WR32			0x63
+#define RSB_CMD_STRA			0xe8
+
+/* DAR fields */
+#define RSB_DAR_RTA(v)			(((v) & 0xff) << 16)
+#define RSB_DAR_DA(v)			((v) & 0xffff)
+
+#define RSB_MAX_FREQ			20000000
+
+#define RSB_CTRL_NAME			"sunxi-rsb"
+
+struct sunxi_rsb_addr_map {
+	u16 hwaddr;
+	u8 rtaddr;
+};
+
+struct sunxi_rsb {
+	struct device *dev;
+	void __iomem *regs;
+	struct clk *clk;
+	struct reset_control *rstc;
+	struct completion complete;
+	struct mutex lock;
+	unsigned int status;
+};
+
+/* bus / slave device related functions */
+static struct bus_type sunxi_rsb_bus;
+
+static int sunxi_rsb_device_match(struct device *dev, struct device_driver *drv)
+{
+	return of_driver_match_device(dev, drv);
+}
+
+static int sunxi_rsb_device_probe(struct device *dev)
+{
+	const struct sunxi_rsb_driver *drv = to_sunxi_rsb_driver(dev->driver);
+	struct sunxi_rsb_device *rdev = to_sunxi_rsb_device(dev);
+	int ret;
+
+	if (!drv->probe)
+		return -ENODEV;
+
+	if (!rdev->irq) {
+		int irq = -ENOENT;
+
+		if (dev->of_node)
+			irq = of_irq_get(dev->of_node, 0);
+
+		if (irq == -EPROBE_DEFER)
+			return irq;
+		if (irq < 0)
+			irq = 0;
+
+		rdev->irq = irq;
+	}
+
+	ret = of_clk_set_defaults(dev->of_node, false);
+	if (ret < 0)
+		return ret;
+
+	return drv->probe(rdev);
+}
+
+static int sunxi_rsb_device_remove(struct device *dev)
+{
+	const struct sunxi_rsb_driver *drv = to_sunxi_rsb_driver(dev->driver);
+
+	return drv->remove(to_sunxi_rsb_device(dev));
+}
+
+static struct bus_type sunxi_rsb_bus = {
+	.name		= RSB_CTRL_NAME,
+	.match		= sunxi_rsb_device_match,
+	.probe		= sunxi_rsb_device_probe,
+	.remove		= sunxi_rsb_device_remove,
+};
+
+static void sunxi_rsb_dev_release(struct device *dev)
+{
+	struct sunxi_rsb_device *rdev = to_sunxi_rsb_device(dev);
+
+	kfree(rdev);
+}
+
+/**
+ * sunxi_rsb_device_create() - allocate and add an RSB device
+ * @rsb:	RSB controller
+ * @node:	RSB slave device node
+ * @hwaddr:	RSB slave hardware address
+ * @rtaddr:	RSB slave runtime address
+ */
+static struct sunxi_rsb_device *sunxi_rsb_device_create(struct sunxi_rsb *rsb,
+		struct device_node *node, u16 hwaddr, u8 rtaddr)
+{
+	int err;
+	struct sunxi_rsb_device *rdev;
+
+	rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
+	if (!rdev)
+		return ERR_PTR(-ENOMEM);
+
+	rdev->rsb = rsb;
+	rdev->hwaddr = hwaddr;
+	rdev->rtaddr = rtaddr;
+	rdev->dev.bus = &sunxi_rsb_bus;
+	rdev->dev.parent = rsb->dev;
+	rdev->dev.of_node = node;
+	rdev->dev.release = sunxi_rsb_dev_release;
+
+	dev_set_name(&rdev->dev, "%s-%x", RSB_CTRL_NAME, hwaddr);
+
+	err = device_register(&rdev->dev);
+	if (err < 0) {
+		dev_err(&rdev->dev, "Can't add %s, status %d\n",
+			dev_name(&rdev->dev), err);
+		goto err_device_add;
+	}
+
+	dev_dbg(&rdev->dev, "device %s registered\n", dev_name(&rdev->dev));
+
+err_device_add:
+	put_device(&rdev->dev);
+
+	return ERR_PTR(err);
+}
+
+/**
+ * sunxi_rsb_device_unregister(): unregister an RSB device
+ * @rdev:	rsb_device to be removed
+ */
+static void sunxi_rsb_device_unregister(struct sunxi_rsb_device *rdev)
+{
+	device_unregister(&rdev->dev);
+}
+
+static int sunxi_rsb_remove_devices(struct device *dev, void *data)
+{
+	struct sunxi_rsb_device *rdev = to_sunxi_rsb_device(dev);
+
+	if (dev->bus == &sunxi_rsb_bus)
+		sunxi_rsb_device_unregister(rdev);
+
+	return 0;
+}
+
+/**
+ * sunxi_rsb_driver_register() - Register device driver with RSB core
+ * @rdrv:	device driver to be associated with slave-device.
+ *
+ * This API will register the client driver with the RSB framework.
+ * It is typically called from the driver's module-init function.
+ */
+int sunxi_rsb_driver_register(struct sunxi_rsb_driver *rdrv)
+{
+	rdrv->driver.bus = &sunxi_rsb_bus;
+	return driver_register(&rdrv->driver);
+}
+EXPORT_SYMBOL_GPL(sunxi_rsb_driver_register);
+
+/* common code that starts a transfer */
+static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
+{
+	if (readl(rsb->regs + RSB_CTRL) & RSB_CTRL_START_TRANS) {
+		dev_dbg(rsb->dev, "RSB transfer still in progress\n");
+		return -EBUSY;
+	}
+
+	reinit_completion(&rsb->complete);
+
+	writel(RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | RSB_INTS_TRANS_OVER,
+	       rsb->regs + RSB_INTE);
+	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
+	       rsb->regs + RSB_CTRL);
+
+	if (!wait_for_completion_io_timeout(&rsb->complete,
+					    msecs_to_jiffies(100))) {
+		dev_dbg(rsb->dev, "RSB timeout\n");
+
+		/* abort the transfer */
+		writel(RSB_CTRL_ABORT_TRANS, rsb->regs + RSB_CTRL);
+
+		/* clear any interrupt flags */
+		writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
+
+		return -ETIMEDOUT;
+	}
+
+	if (rsb->status & RSB_INTS_LOAD_BSY) {
+		dev_dbg(rsb->dev, "RSB busy\n");
+		return -EBUSY;
+	}
+
+	if (rsb->status & RSB_INTS_TRANS_ERR) {
+		if (rsb->status & RSB_INTS_TRANS_ERR_ACK) {
+			dev_dbg(rsb->dev, "RSB slave nack\n");
+			return -EINVAL;
+		}
+
+		if (rsb->status & RSB_INTS_TRANS_ERR_DATA) {
+			dev_dbg(rsb->dev, "RSB transfer data error\n");
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+static int sunxi_rsb_read(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
+			  u32 *buf, size_t len)
+{
+	u32 cmd;
+	int ret;
+
+	if (!buf)
+		return -EINVAL;
+
+	switch (len) {
+	case 1:
+		cmd = RSB_CMD_RD8;
+		break;
+	case 2:
+		cmd = RSB_CMD_RD16;
+		break;
+	case 4:
+		cmd = RSB_CMD_RD32;
+		break;
+	default:
+		dev_err(rsb->dev, "Invalid access width: %d\n", len);
+		return -EINVAL;
+	}
+
+	mutex_lock(&rsb->lock);
+
+	writel(addr, rsb->regs + RSB_ADDR);
+	writel(RSB_DAR_RTA(rtaddr), rsb->regs + RSB_DAR);
+	writel(cmd, rsb->regs + RSB_CMD);
+
+	ret = _sunxi_rsb_run_xfer(rsb);
+	if (ret)
+		goto out;
+
+	*buf = readl(rsb->regs + RSB_DATA);
+
+	mutex_unlock(&rsb->lock);
+
+out:
+	return ret;
+}
+
+static int sunxi_rsb_write(struct sunxi_rsb *rsb, u8 rtaddr, u8 addr,
+			   const u32 *buf, size_t len)
+{
+	u32 cmd;
+	int ret;
+
+	if (!buf)
+		return -EINVAL;
+
+	switch (len) {
+	case 1:
+		cmd = RSB_CMD_WR8;
+		break;
+	case 2:
+		cmd = RSB_CMD_WR16;
+		break;
+	case 4:
+		cmd = RSB_CMD_WR32;
+		break;
+	default:
+		dev_err(rsb->dev, "Invalid access width: %d\n", len);
+		return -EINVAL;
+	}
+
+	mutex_lock(&rsb->lock);
+
+	writel(addr, rsb->regs + RSB_ADDR);
+	writel(RSB_DAR_RTA(rtaddr), rsb->regs + RSB_DAR);
+	writel(*buf, rsb->regs + RSB_DATA);
+	writel(cmd, rsb->regs + RSB_CMD);
+	ret = _sunxi_rsb_run_xfer(rsb);
+
+	mutex_unlock(&rsb->lock);
+
+	return ret;
+}
+
+/* RSB regmap functions */
+struct sunxi_rsb_ctx {
+	struct sunxi_rsb_device *rdev;
+	int size;
+};
+
+static int regmap_sunxi_rsb_reg_read(void *context, unsigned int reg,
+				     unsigned int *val)
+{
+	struct sunxi_rsb_ctx *ctx = context;
+	struct sunxi_rsb_device *rdev = ctx->rdev;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	return sunxi_rsb_read(rdev->rsb, rdev->rtaddr, reg, val, ctx->size);
+}
+
+static int regmap_sunxi_rsb_reg_write(void *context, unsigned int reg,
+				      unsigned int val)
+{
+	struct sunxi_rsb_ctx *ctx = context;
+	struct sunxi_rsb_device *rdev = ctx->rdev;
+
+	return sunxi_rsb_write(rdev->rsb, rdev->rtaddr, reg, &val, ctx->size);
+}
+
+static void regmap_sunxi_rsb_free_ctx(void *context)
+{
+	struct sunxi_rsb_ctx *ctx = context;
+
+	kfree(ctx);
+}
+
+static struct regmap_bus regmap_sunxi_rsb = {
+	.reg_write = regmap_sunxi_rsb_reg_write,
+	.reg_read = regmap_sunxi_rsb_reg_read,
+	.free_context = regmap_sunxi_rsb_free_ctx,
+	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+static struct sunxi_rsb_ctx *regmap_sunxi_rsb_init_ctx(struct sunxi_rsb_device *rdev,
+		const struct regmap_config *config)
+{
+	struct sunxi_rsb_ctx *ctx;
+
+	switch (config->val_bits) {
+	case 8:
+	case 16:
+	case 32:
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	ctx->rdev = rdev;
+	ctx->size = config->val_bits / 8;
+
+	return ctx;
+}
+
+struct regmap *__devm_regmap_init_sunxi_rsb(struct sunxi_rsb_device *rdev,
+					    const struct regmap_config *config,
+					    struct lock_class_key *lock_key,
+					    const char *lock_name)
+{
+	struct sunxi_rsb_ctx *ctx = regmap_sunxi_rsb_init_ctx(rdev, config);
+
+	if (IS_ERR(ctx))
+		return ERR_CAST(ctx);
+
+	return __devm_regmap_init(&rdev->dev, &regmap_sunxi_rsb, ctx, config,
+				  lock_key, lock_name);
+}
+EXPORT_SYMBOL_GPL(__devm_regmap_init_sunxi_rsb);
+
+/* RSB controller driver functions */
+static irqreturn_t sunxi_rsb_irq(int irq, void *dev_id)
+{
+	struct sunxi_rsb *rsb = dev_id;
+	u32 status;
+
+	status = readl(rsb->regs + RSB_INTS);
+	rsb->status = status;
+
+	/* Clear interrupts */
+	status &= (RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
+		   RSB_INTS_TRANS_OVER);
+	writel(status, rsb->regs + RSB_INTS);
+
+	complete(&rsb->complete);
+
+	return IRQ_HANDLED;
+}
+
+static int sunxi_rsb_init_device_mode(struct sunxi_rsb *rsb)
+{
+	int ret = 0;
+	u32 reg;
+
+	/* send init sequence */
+	writel(RSB_DMCR_DEVICE_START | RSB_DMCR_MODE_DATA |
+	       RSB_DMCR_MODE_REG | RSB_DMCR_DEV_ADDR, rsb->regs + RSB_DMCR);
+
+	readl_poll_timeout(rsb->regs + RSB_DMCR, reg,
+			   !(reg & RSB_DMCR_DEVICE_START), 100, 250000);
+	if (reg & RSB_DMCR_DEVICE_START)
+		ret = -ETIMEDOUT;
+
+	/* clear interrupt status bits */
+	writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
+
+	return ret;
+}
+
+/*
+ * There are 15 valid runtime addresses, though Allwinner typically
+ * skips the first, for unknown reasons, and uses the following three.
+ *
+ * 0x17, 0x2d, 0x3a, 0x4e, 0x59, 0x63, 0x74, 0x8b,
+ * 0x9c, 0xa6, 0xb1, 0xc5, 0xd2, 0xe8, 0xff
+ *
+ * No designs with 2 RSB slave devices sharing identical hardware
+ * addresses on the same bus have been seen in the wild. All designs
+ * use 0x2d for the primary PMIC, 0x3a for the secondary PMIC if
+ * there is one, and 0x45 for peripheral ICs.
+ *
+ * The hardware does not seem to support re-setting runtime addresses.
+ * Attempts to do so result in the slave devices returning a NACK.
+ * Hence we just hardcode the mapping here, like Allwinner does.
+ */
+
+static const struct sunxi_rsb_addr_map sunxi_rsb_addr_maps[] = {
+	{ 0x3e3, 0x2d }, /* Primary PMIC: AXP223, AXP809, AXP81X, ... */
+	{ 0x745, 0x3a }, /* Secondary PMIC: AXP806, ... */
+	{ 0xe89, 0x45 }, /* Peripheral IC: AC100, ... */
+};
+
+static u8 sunxi_rsb_get_rtaddr(u16 hwaddr)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sunxi_rsb_addr_maps); i++)
+		if (hwaddr == sunxi_rsb_addr_maps[i].hwaddr)
+			return sunxi_rsb_addr_maps[i].rtaddr;
+
+	return 0; /* 0 is an invalid runtime address */
+}
+
+static int of_rsb_register_devices(struct sunxi_rsb *rsb)
+{
+	struct device *dev = rsb->dev;
+	struct device_node *child, *np = dev->of_node;
+	u32 hwaddr;
+	u8 rtaddr;
+	int ret;
+
+	if (!np)
+		return -EINVAL;
+
+	/* Runtime addresses for all slaves should be set first */
+	for_each_available_child_of_node(np, child) {
+		dev_dbg(dev, "setting child %s runtime address\n",
+			child->full_name);
+
+		ret = of_property_read_u32(child, "reg", &hwaddr);
+		if (ret) {
+			dev_err(dev, "%s: invalid 'reg' property: %d\n",
+				child->full_name, ret);
+			continue;
+		}
+
+		rtaddr = sunxi_rsb_get_rtaddr(hwaddr);
+		if (!rtaddr) {
+			dev_err(dev, "%s: unknown hardware device address\n",
+				child->full_name);
+			continue;
+		}
+
+		/*
+		 * Since no devices have been registered yet, we are the
+		 * only ones using the bus, we can skip locking the bus.
+		 */
+
+		/* setup command parameters */
+		writel(RSB_CMD_STRA, rsb->regs + RSB_CMD);
+		writel(RSB_DAR_RTA(rtaddr) | RSB_DAR_DA(hwaddr),
+		       rsb->regs + RSB_DAR);
+
+		/* send command */
+		ret = _sunxi_rsb_run_xfer(rsb);
+		if (ret)
+			dev_warn(dev, "%s: set runtime address failed: %d\n",
+				 child->full_name, ret);
+	}
+
+	/* Then we start adding devices and probing them */
+	for_each_available_child_of_node(np, child) {
+		struct sunxi_rsb_device *rdev;
+
+		dev_dbg(dev, "adding child %s\n", child->full_name);
+
+		ret = of_property_read_u32(child, "reg", &hwaddr);
+		if (ret)
+			continue;
+
+		rtaddr = sunxi_rsb_get_rtaddr(hwaddr);
+		if (!rtaddr)
+			continue;
+
+		rdev = sunxi_rsb_device_create(rsb, child, hwaddr, rtaddr);
+		if (IS_ERR(rdev))
+			dev_err(dev, "failed to add child device %s: %ld\n",
+				child->full_name, PTR_ERR(rdev));
+	}
+
+	return 0;
+}
+
+static const struct of_device_id sunxi_rsb_of_match_table[] = {
+	{ .compatible = "allwinner,sun8i-a23-rsb" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sunxi_rsb_of_match_table);
+
+static int sunxi_rsb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct resource *r;
+	struct sunxi_rsb *rsb;
+	unsigned long p_clk_freq;
+	u32 clk_delay, clk_freq = 3000000;
+	int clk_div, irq, ret;
+	u32 reg;
+
+	of_property_read_u32(np, "clock-frequency", &clk_freq);
+	if (clk_freq > RSB_MAX_FREQ) {
+		dev_err(dev,
+			"clock-frequency (%u Hz) is too high (max = 20MHz)\n",
+			clk_freq);
+		return -EINVAL;
+	}
+
+	rsb = devm_kzalloc(dev, sizeof(*rsb), GFP_KERNEL);
+	if (!rsb)
+		return -ENOMEM;
+
+	rsb->dev = dev;
+	platform_set_drvdata(pdev, rsb);
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rsb->regs = devm_ioremap_resource(dev, r);
+	if (IS_ERR(rsb->regs))
+		return PTR_ERR(rsb->regs);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(dev, "failed to retrieve irq: %d\n", irq);
+		return irq;
+	}
+
+	rsb->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(rsb->clk)) {
+		ret = PTR_ERR(rsb->clk);
+		dev_err(dev, "failed to retrieve clk: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(rsb->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable clk: %d\n", ret);
+		return ret;
+	}
+
+	p_clk_freq = clk_get_rate(rsb->clk);
+
+	rsb->rstc = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(rsb->rstc)) {
+		ret = PTR_ERR(rsb->rstc);
+		dev_err(dev, "failed to retrieve reset controller: %d\n", ret);
+		goto err_clk_disable;
+	}
+
+	ret = reset_control_deassert(rsb->rstc);
+	if (ret) {
+		dev_err(dev, "failed to deassert reset line: %d\n", ret);
+		goto err_clk_disable;
+	}
+
+	init_completion(&rsb->complete);
+	mutex_init(&rsb->lock);
+
+	/* reset the controller */
+	writel(RSB_CTRL_SOFT_RST, rsb->regs + RSB_CTRL);
+	readl_poll_timeout(rsb->regs + RSB_CTRL, reg,
+			   !(reg & RSB_CTRL_SOFT_RST), 1000, 100000);
+
+	/*
+	 * Clock frequency and delay calculation code is from
+	 * Allwinner U-boot sources.
+	 *
+	 * From A83 user manual:
+	 * bus clock frequency = parent clock frequency / (2 * (divider + 1))
+	 */
+	clk_div = p_clk_freq / clk_freq / 2;
+	if (!clk_div)
+		clk_div = 1;
+	else if (clk_div > RSB_CCR_MAX_CLK_DIV + 1)
+		clk_div = RSB_CCR_MAX_CLK_DIV + 1;
+
+	clk_delay = clk_div >> 1;
+	if (!clk_delay)
+		clk_delay = 1;
+
+	dev_info(dev, "RSB running at %lu Hz\n", p_clk_freq / clk_div / 2);
+	writel(RSB_CCR_SDA_OUT_DELAY(clk_delay) | RSB_CCR_CLK_DIV(clk_div - 1),
+	       rsb->regs + RSB_CCR);
+
+	ret = devm_request_irq(dev, irq, sunxi_rsb_irq, 0, RSB_CTRL_NAME, rsb);
+	if (ret) {
+		dev_err(dev, "can't register interrupt handler irq %d: %d\n",
+			irq, ret);
+		goto err_reset_assert;
+	}
+
+	/* initialize all devices on the bus into RSB mode */
+	ret = sunxi_rsb_init_device_mode(rsb);
+	if (ret)
+		dev_warn(dev, "Initialize device mode failed: %d\n", ret);
+
+	of_rsb_register_devices(rsb);
+
+	return 0;
+
+err_reset_assert:
+	reset_control_assert(rsb->rstc);
+
+err_clk_disable:
+	clk_disable_unprepare(rsb->clk);
+
+	return ret;
+}
+
+static int sunxi_rsb_remove(struct platform_device *pdev)
+{
+	struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
+
+	device_for_each_child(rsb->dev, NULL, sunxi_rsb_remove_devices);
+	reset_control_assert(rsb->rstc);
+	clk_disable_unprepare(rsb->clk);
+
+	return 0;
+}
+
+static struct platform_driver sunxi_rsb_driver = {
+	.probe = sunxi_rsb_probe,
+	.remove	= sunxi_rsb_remove,
+	.driver	= {
+		.name = RSB_CTRL_NAME,
+		.of_match_table = sunxi_rsb_of_match_table,
+	},
+};
+
+static int __init sunxi_rsb_init(void)
+{
+	int ret;
+
+	ret = bus_register(&sunxi_rsb_bus);
+	if (ret) {
+		pr_err("failed to register sunxi sunxi_rsb bus: %d\n", ret);
+		return ret;
+	}
+
+	return platform_driver_register(&sunxi_rsb_driver);
+}
+module_init(sunxi_rsb_init);
+
+static void __exit sunxi_rsb_exit(void)
+{
+	platform_driver_unregister(&sunxi_rsb_driver);
+	bus_unregister(&sunxi_rsb_bus);
+}
+module_exit(sunxi_rsb_exit);
+
+MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
+MODULE_DESCRIPTION("Allwinner sunXi Reduced Serial Bus controller driver");
+MODULE_LICENSE("GPL v2");