path: root/drivers/bus/sunxi-rsb.c

/*
 * 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,
	.uevent		= of_device_uevent_modalias,
};

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)