drivers/i2c/busses/i2c-sun6i-p2wi.c - linux - Git at Google

 /*
  * P2WI (Push-Pull Two Wire Interface) bus driver.
  *
  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
  *
  * 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 P2WI controller looks like an SMBus controller which only supports byte
  * data transfers. But, it differs from standard SMBus protocol on several
  * aspects:
  * - it supports only one slave device, and thus drop the address field
  * - it adds a parity bit every 8bits of data
  * - 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 byte transfer
  *
  * This means this bus cannot be used to interface with standard SMBus
  * devices (the only known device to support this interface is the AXP221
  * PMIC).
  *
  */
 #include <linux/clk.h>
 #include <linux/i2c.h>
 #include <linux/io.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>


 /* P2WI registers */
 #define P2WI_CTRL		0x0
 #define P2WI_CCR		0x4
 #define P2WI_INTE		0x8
 #define P2WI_INTS		0xc
 #define P2WI_DADDR0		0x10
 #define P2WI_DADDR1		0x14
 #define P2WI_DLEN		0x18
 #define P2WI_DATA0		0x1c
 #define P2WI_DATA1		0x20
 #define P2WI_LCR		0x24
 #define P2WI_PMCR		0x28

 /* CTRL fields */
 #define P2WI_CTRL_START_TRANS		BIT(7)
 #define P2WI_CTRL_ABORT_TRANS		BIT(6)
 #define P2WI_CTRL_GLOBAL_INT_ENB	BIT(1)
 #define P2WI_CTRL_SOFT_RST		BIT(0)

 /* CLK CTRL fields */
 #define P2WI_CCR_SDA_OUT_DELAY(v)	(((v) & 0x7) << 8)
 #define P2WI_CCR_MAX_CLK_DIV		0xff
 #define P2WI_CCR_CLK_DIV(v)		((v) & P2WI_CCR_MAX_CLK_DIV)

 /* STATUS fields */
 #define P2WI_INTS_TRANS_ERR_ID(v)	(((v) >> 8) & 0xff)
 #define P2WI_INTS_LOAD_BSY		BIT(2)
 #define P2WI_INTS_TRANS_ERR		BIT(1)
 #define P2WI_INTS_TRANS_OVER		BIT(0)

 /* DATA LENGTH fields*/
 #define P2WI_DLEN_READ			BIT(4)
 #define P2WI_DLEN_DATA_LENGTH(v)	((v - 1) & 0x7)

 /* LINE CTRL fields*/
 #define P2WI_LCR_SCL_STATE		BIT(5)
 #define P2WI_LCR_SDA_STATE		BIT(4)
 #define P2WI_LCR_SCL_CTL		BIT(3)
 #define P2WI_LCR_SCL_CTL_EN		BIT(2)
 #define P2WI_LCR_SDA_CTL		BIT(1)
 #define P2WI_LCR_SDA_CTL_EN		BIT(0)

 /* PMU MODE CTRL fields */
 #define P2WI_PMCR_PMU_INIT_SEND		BIT(31)
 #define P2WI_PMCR_PMU_INIT_DATA(v)	(((v) & 0xff) << 16)
 #define P2WI_PMCR_PMU_MODE_REG(v)	(((v) & 0xff) << 8)
 #define P2WI_PMCR_PMU_DEV_ADDR(v)	((v) & 0xff)

 #define P2WI_MAX_FREQ			6000000

 struct p2wi {
 	struct i2c_adapter adapter;
 	struct completion complete;
 	unsigned int status;
 	void __iomem *regs;
 	struct clk *clk;
 	struct reset_control *rstc;
 	int slave_addr;
 };

 static irqreturn_t p2wi_interrupt(int irq, void *dev_id)
 {
 	struct p2wi *p2wi = dev_id;
 	unsigned long status;

 	status = readl(p2wi->regs + P2WI_INTS);
 	p2wi->status = status;

 	/* Clear interrupts */
 	status &= (P2WI_INTS_LOAD_BSY | P2WI_INTS_TRANS_ERR |
 		   P2WI_INTS_TRANS_OVER);
 	writel(status, p2wi->regs + P2WI_INTS);

 	complete(&p2wi->complete);

 	return IRQ_HANDLED;
 }

 static u32 p2wi_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_SMBUS_BYTE_DATA;
 }

 static int p2wi_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 			   unsigned short flags, char read_write,
 			   u8 command, int size, union i2c_smbus_data *data)
 {
 	struct p2wi *p2wi = i2c_get_adapdata(adap);
 	unsigned long dlen = P2WI_DLEN_DATA_LENGTH(1);

 	if (p2wi->slave_addr >= 0 && addr != p2wi->slave_addr) {
 		dev_err(&adap->dev, "invalid P2WI address\n");
 		return -EINVAL;
 	}

 	if (!data)
 		return -EINVAL;

 	writel(command, p2wi->regs + P2WI_DADDR0);

 	if (read_write == I2C_SMBUS_READ)
 		dlen |= P2WI_DLEN_READ;
 	else
 		writel(data->byte, p2wi->regs + P2WI_DATA0);

 	writel(dlen, p2wi->regs + P2WI_DLEN);

 	if (readl(p2wi->regs + P2WI_CTRL) & P2WI_CTRL_START_TRANS) {
 		dev_err(&adap->dev, "P2WI bus busy\n");
 		return -EBUSY;
 	}

 	reinit_completion(&p2wi->complete);

 	writel(P2WI_INTS_LOAD_BSY | P2WI_INTS_TRANS_ERR | P2WI_INTS_TRANS_OVER,
 	       p2wi->regs + P2WI_INTE);

 	writel(P2WI_CTRL_START_TRANS | P2WI_CTRL_GLOBAL_INT_ENB,
 	       p2wi->regs + P2WI_CTRL);

 	wait_for_completion(&p2wi->complete);

 	if (p2wi->status & P2WI_INTS_LOAD_BSY) {
 		dev_err(&adap->dev, "P2WI bus busy\n");
 		return -EBUSY;
 	}

 	if (p2wi->status & P2WI_INTS_TRANS_ERR) {
 		dev_err(&adap->dev, "P2WI bus xfer error\n");
 		return -ENXIO;
 	}

 	if (read_write == I2C_SMBUS_READ)
 		data->byte = readl(p2wi->regs + P2WI_DATA0);

 	return 0;
 }

 static const struct i2c_algorithm p2wi_algo = {
 	.smbus_xfer = p2wi_smbus_xfer,
 	.functionality = p2wi_functionality,
 };

 static const struct of_device_id p2wi_of_match_table[] = {
 	{ .compatible = "allwinner,sun6i-a31-p2wi" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, p2wi_of_match_table);

 static int p2wi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct device_node *childnp;
 	unsigned long parent_clk_freq;
 	u32 clk_freq = I2C_MAX_STANDARD_MODE_FREQ;
 	struct p2wi *p2wi;
 	u32 slave_addr;
 	int clk_div;
 	int irq;
 	int ret;

 	of_property_read_u32(np, "clock-frequency", &clk_freq);
 	if (clk_freq > P2WI_MAX_FREQ) {
 		dev_err(dev,
 			"required clock-frequency (%u Hz) is too high (max = 6MHz)",
 			clk_freq);
 		return -EINVAL;
 	}

 	if (of_get_child_count(np) > 1) {
 		dev_err(dev, "P2WI only supports one slave device\n");
 		return -EINVAL;
 	}

 	p2wi = devm_kzalloc(dev, sizeof(struct p2wi), GFP_KERNEL);
 	if (!p2wi)
 		return -ENOMEM;

 	p2wi->slave_addr = -1;

 	/*
 	 * Authorize a p2wi node without any children to be able to use an
 	 * i2c-dev from userpace.
 	 * In this case the slave_addr is set to -1 and won't be checked when
 	 * launching a P2WI transfer.
 	 */
 	childnp = of_get_next_available_child(np, NULL);
 	if (childnp) {
 		ret = of_property_read_u32(childnp, "reg", &slave_addr);
 		if (ret) {
 			dev_err(dev, "invalid slave address on node %pOF\n",
 				childnp);
 			return -EINVAL;
 		}

 		p2wi->slave_addr = slave_addr;
 	}

 	p2wi->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(p2wi->regs))
 		return PTR_ERR(p2wi->regs);

 	strscpy(p2wi->adapter.name, pdev->name, sizeof(p2wi->adapter.name));
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
 		return irq;

 	p2wi->clk = devm_clk_get_enabled(dev, NULL);
 	if (IS_ERR(p2wi->clk)) {
 		ret = PTR_ERR(p2wi->clk);
 		dev_err(dev, "failed to enable clk: %d\n", ret);
 		return ret;
 	}

 	parent_clk_freq = clk_get_rate(p2wi->clk);

 	p2wi->rstc = devm_reset_control_get_exclusive(dev, NULL);
 	if (IS_ERR(p2wi->rstc)) {
 		dev_err(dev, "failed to retrieve reset controller: %pe\n",
 			p2wi->rstc);
 		return PTR_ERR(p2wi->rstc);
 	}

 	ret = reset_control_deassert(p2wi->rstc);
 	if (ret) {
 		dev_err(dev, "failed to deassert reset line: %d\n", ret);
 		return ret;
 	}

 	init_completion(&p2wi->complete);
 	p2wi->adapter.dev.parent = dev;
 	p2wi->adapter.algo = &p2wi_algo;
 	p2wi->adapter.owner = THIS_MODULE;
 	p2wi->adapter.dev.of_node = pdev->dev.of_node;
 	platform_set_drvdata(pdev, p2wi);
 	i2c_set_adapdata(&p2wi->adapter, p2wi);

 	ret = devm_request_irq(dev, irq, p2wi_interrupt, 0, pdev->name, p2wi);
 	if (ret) {
 		dev_err(dev, "can't register interrupt handler irq%d: %d\n",
 			irq, ret);
 		goto err_reset_assert;
 	}

 	writel(P2WI_CTRL_SOFT_RST, p2wi->regs + P2WI_CTRL);

 	clk_div = parent_clk_freq / clk_freq;
 	if (!clk_div) {
 		dev_warn(dev,
 			 "clock-frequency is too high, setting it to %lu Hz\n",
 			 parent_clk_freq);
 		clk_div = 1;
 	} else if (clk_div > P2WI_CCR_MAX_CLK_DIV) {
 		dev_warn(dev,
 			 "clock-frequency is too low, setting it to %lu Hz\n",
 			 parent_clk_freq / P2WI_CCR_MAX_CLK_DIV);
 		clk_div = P2WI_CCR_MAX_CLK_DIV;
 	}

 	writel(P2WI_CCR_SDA_OUT_DELAY(1) | P2WI_CCR_CLK_DIV(clk_div),
 	       p2wi->regs + P2WI_CCR);

 	ret = i2c_add_adapter(&p2wi->adapter);
 	if (!ret)
 		return 0;

 err_reset_assert:
 	reset_control_assert(p2wi->rstc);

 	return ret;
 }

 static void p2wi_remove(struct platform_device *dev)
 {
 	struct p2wi *p2wi = platform_get_drvdata(dev);

 	reset_control_assert(p2wi->rstc);
 	i2c_del_adapter(&p2wi->adapter);
 }

 static struct platform_driver p2wi_driver = {
 	.probe	= p2wi_probe,
 	.remove_new = p2wi_remove,
 	.driver	= {
 		.name = "i2c-sunxi-p2wi",
 		.of_match_table = p2wi_of_match_table,
 	},
 };
 module_platform_driver(p2wi_driver);

 MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
 MODULE_DESCRIPTION("Allwinner P2WI driver");
 MODULE_LICENSE("GPL v2");
	/*
	* P2WI (Push-Pull Two Wire Interface) bus driver.
	*
	* Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
	*
	* 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 P2WI controller looks like an SMBus controller which only supports byte
	* data transfers. But, it differs from standard SMBus protocol on several
	* aspects:
	* - it supports only one slave device, and thus drop the address field
	* - it adds a parity bit every 8bits of data
	* - 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 byte transfer
	*
	* This means this bus cannot be used to interface with standard SMBus
	* devices (the only known device to support this interface is the AXP221
	* PMIC).
	*
	*/
	#include <linux/clk.h>
	#include <linux/i2c.h>
	#include <linux/io.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/reset.h>


	/* P2WI registers */
	#define P2WI_CTRL 0x0
	#define P2WI_CCR 0x4
	#define P2WI_INTE 0x8
	#define P2WI_INTS 0xc
	#define P2WI_DADDR0 0x10
	#define P2WI_DADDR1 0x14
	#define P2WI_DLEN 0x18
	#define P2WI_DATA0 0x1c
	#define P2WI_DATA1 0x20
	#define P2WI_LCR 0x24
	#define P2WI_PMCR 0x28

	/* CTRL fields */
	#define P2WI_CTRL_START_TRANS BIT(7)
	#define P2WI_CTRL_ABORT_TRANS BIT(6)
	#define P2WI_CTRL_GLOBAL_INT_ENB BIT(1)
	#define P2WI_CTRL_SOFT_RST BIT(0)

	/* CLK CTRL fields */
	#define P2WI_CCR_SDA_OUT_DELAY(v) (((v) & 0x7) << 8)
	#define P2WI_CCR_MAX_CLK_DIV 0xff
	#define P2WI_CCR_CLK_DIV(v) ((v) & P2WI_CCR_MAX_CLK_DIV)

	/* STATUS fields */
	#define P2WI_INTS_TRANS_ERR_ID(v) (((v) >> 8) & 0xff)
	#define P2WI_INTS_LOAD_BSY BIT(2)
	#define P2WI_INTS_TRANS_ERR BIT(1)
	#define P2WI_INTS_TRANS_OVER BIT(0)

	/* DATA LENGTH fields*/
	#define P2WI_DLEN_READ BIT(4)
	#define P2WI_DLEN_DATA_LENGTH(v) ((v - 1) & 0x7)

	/* LINE CTRL fields*/
	#define P2WI_LCR_SCL_STATE BIT(5)
	#define P2WI_LCR_SDA_STATE BIT(4)
	#define P2WI_LCR_SCL_CTL BIT(3)
	#define P2WI_LCR_SCL_CTL_EN BIT(2)
	#define P2WI_LCR_SDA_CTL BIT(1)
	#define P2WI_LCR_SDA_CTL_EN BIT(0)

	/* PMU MODE CTRL fields */
	#define P2WI_PMCR_PMU_INIT_SEND BIT(31)
	#define P2WI_PMCR_PMU_INIT_DATA(v) (((v) & 0xff) << 16)
	#define P2WI_PMCR_PMU_MODE_REG(v) (((v) & 0xff) << 8)
	#define P2WI_PMCR_PMU_DEV_ADDR(v) ((v) & 0xff)

	#define P2WI_MAX_FREQ 6000000

	struct p2wi {
	struct i2c_adapter adapter;
	struct completion complete;
	unsigned int status;
	void __iomem *regs;
	struct clk *clk;
	struct reset_control *rstc;
	int slave_addr;
	};

	static irqreturn_t p2wi_interrupt(int irq, void *dev_id)
	{
	struct p2wi *p2wi = dev_id;
	unsigned long status;

	status = readl(p2wi->regs + P2WI_INTS);
	p2wi->status = status;

	/* Clear interrupts */
	status &= (P2WI_INTS_LOAD_BSY \| P2WI_INTS_TRANS_ERR \|
	P2WI_INTS_TRANS_OVER);
	writel(status, p2wi->regs + P2WI_INTS);

	complete(&p2wi->complete);

	return IRQ_HANDLED;
	}

	static u32 p2wi_functionality(struct i2c_adapter *adap)
	{
	return I2C_FUNC_SMBUS_BYTE_DATA;
	}

	static int p2wi_smbus_xfer(struct i2c_adapter *adap, u16 addr,
	unsigned short flags, char read_write,
	u8 command, int size, union i2c_smbus_data *data)
	{
	struct p2wi *p2wi = i2c_get_adapdata(adap);
	unsigned long dlen = P2WI_DLEN_DATA_LENGTH(1);

	if (p2wi->slave_addr >= 0 && addr != p2wi->slave_addr) {
	dev_err(&adap->dev, "invalid P2WI address\n");
	return -EINVAL;
	}

	if (!data)
	return -EINVAL;

	writel(command, p2wi->regs + P2WI_DADDR0);

	if (read_write == I2C_SMBUS_READ)
	dlen \|= P2WI_DLEN_READ;
	else
	writel(data->byte, p2wi->regs + P2WI_DATA0);

	writel(dlen, p2wi->regs + P2WI_DLEN);

	if (readl(p2wi->regs + P2WI_CTRL) & P2WI_CTRL_START_TRANS) {
	dev_err(&adap->dev, "P2WI bus busy\n");
	return -EBUSY;
	}

	reinit_completion(&p2wi->complete);

	writel(P2WI_INTS_LOAD_BSY \| P2WI_INTS_TRANS_ERR \| P2WI_INTS_TRANS_OVER,
	p2wi->regs + P2WI_INTE);

	writel(P2WI_CTRL_START_TRANS \| P2WI_CTRL_GLOBAL_INT_ENB,
	p2wi->regs + P2WI_CTRL);

	wait_for_completion(&p2wi->complete);

	if (p2wi->status & P2WI_INTS_LOAD_BSY) {
	dev_err(&adap->dev, "P2WI bus busy\n");
	return -EBUSY;
	}

	if (p2wi->status & P2WI_INTS_TRANS_ERR) {
	dev_err(&adap->dev, "P2WI bus xfer error\n");
	return -ENXIO;
	}

	if (read_write == I2C_SMBUS_READ)
	data->byte = readl(p2wi->regs + P2WI_DATA0);

	return 0;
	}

	static const struct i2c_algorithm p2wi_algo = {
	.smbus_xfer = p2wi_smbus_xfer,
	.functionality = p2wi_functionality,
	};

	static const struct of_device_id p2wi_of_match_table[] = {
	{ .compatible = "allwinner,sun6i-a31-p2wi" },
	{}
	};
	MODULE_DEVICE_TABLE(of, p2wi_of_match_table);

	static int p2wi_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct device_node *childnp;
	unsigned long parent_clk_freq;
	u32 clk_freq = I2C_MAX_STANDARD_MODE_FREQ;
	struct p2wi *p2wi;
	u32 slave_addr;
	int clk_div;
	int irq;
	int ret;

	of_property_read_u32(np, "clock-frequency", &clk_freq);
	if (clk_freq > P2WI_MAX_FREQ) {
	dev_err(dev,
	"required clock-frequency (%u Hz) is too high (max = 6MHz)",
	clk_freq);
	return -EINVAL;
	}

	if (of_get_child_count(np) > 1) {
	dev_err(dev, "P2WI only supports one slave device\n");
	return -EINVAL;
	}

	p2wi = devm_kzalloc(dev, sizeof(struct p2wi), GFP_KERNEL);
	if (!p2wi)
	return -ENOMEM;

	p2wi->slave_addr = -1;

	/*
	* Authorize a p2wi node without any children to be able to use an
	* i2c-dev from userpace.
	* In this case the slave_addr is set to -1 and won't be checked when
	* launching a P2WI transfer.
	*/
	childnp = of_get_next_available_child(np, NULL);
	if (childnp) {
	ret = of_property_read_u32(childnp, "reg", &slave_addr);
	if (ret) {
	dev_err(dev, "invalid slave address on node %pOF\n",
	childnp);
	return -EINVAL;
	}

	p2wi->slave_addr = slave_addr;
	}

	p2wi->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(p2wi->regs))
	return PTR_ERR(p2wi->regs);

	strscpy(p2wi->adapter.name, pdev->name, sizeof(p2wi->adapter.name));
	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
	return irq;

	p2wi->clk = devm_clk_get_enabled(dev, NULL);
	if (IS_ERR(p2wi->clk)) {
	ret = PTR_ERR(p2wi->clk);
	dev_err(dev, "failed to enable clk: %d\n", ret);
	return ret;
	}

	parent_clk_freq = clk_get_rate(p2wi->clk);

	p2wi->rstc = devm_reset_control_get_exclusive(dev, NULL);
	if (IS_ERR(p2wi->rstc)) {
	dev_err(dev, "failed to retrieve reset controller: %pe\n",
	p2wi->rstc);
	return PTR_ERR(p2wi->rstc);
	}

	ret = reset_control_deassert(p2wi->rstc);
	if (ret) {
	dev_err(dev, "failed to deassert reset line: %d\n", ret);
	return ret;
	}

	init_completion(&p2wi->complete);
	p2wi->adapter.dev.parent = dev;
	p2wi->adapter.algo = &p2wi_algo;
	p2wi->adapter.owner = THIS_MODULE;
	p2wi->adapter.dev.of_node = pdev->dev.of_node;
	platform_set_drvdata(pdev, p2wi);
	i2c_set_adapdata(&p2wi->adapter, p2wi);

	ret = devm_request_irq(dev, irq, p2wi_interrupt, 0, pdev->name, p2wi);
	if (ret) {
	dev_err(dev, "can't register interrupt handler irq%d: %d\n",
	irq, ret);
	goto err_reset_assert;
	}

	writel(P2WI_CTRL_SOFT_RST, p2wi->regs + P2WI_CTRL);

	clk_div = parent_clk_freq / clk_freq;
	if (!clk_div) {
	dev_warn(dev,
	"clock-frequency is too high, setting it to %lu Hz\n",
	parent_clk_freq);
	clk_div = 1;
	} else if (clk_div > P2WI_CCR_MAX_CLK_DIV) {
	dev_warn(dev,
	"clock-frequency is too low, setting it to %lu Hz\n",
	parent_clk_freq / P2WI_CCR_MAX_CLK_DIV);
	clk_div = P2WI_CCR_MAX_CLK_DIV;
	}

	writel(P2WI_CCR_SDA_OUT_DELAY(1) \| P2WI_CCR_CLK_DIV(clk_div),
	p2wi->regs + P2WI_CCR);

	ret = i2c_add_adapter(&p2wi->adapter);
	if (!ret)
	return 0;

	err_reset_assert:
	reset_control_assert(p2wi->rstc);

	return ret;
	}

	static void p2wi_remove(struct platform_device *dev)
	{
	struct p2wi *p2wi = platform_get_drvdata(dev);

	reset_control_assert(p2wi->rstc);
	i2c_del_adapter(&p2wi->adapter);
	}

	static struct platform_driver p2wi_driver = {
	.probe = p2wi_probe,
	.remove_new = p2wi_remove,
	.driver = {
	.name = "i2c-sunxi-p2wi",
	.of_match_table = p2wi_of_match_table,
	},
	};
	module_platform_driver(p2wi_driver);

	MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
	MODULE_DESCRIPTION("Allwinner P2WI driver");
	MODULE_LICENSE("GPL v2");