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linux-sg2042/drivers/bus/sunxi-rsb.c

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/*
* 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");
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