i2c: loongson: Add LS7A i2c driver support

LoongArch inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6BWFP

--------------------------------

Change-Id: Ia57bb17a0663d038c61cdd52ce5b6fe63a979dde
Signed-off-by: NJuxin Gao <gaojuxin@loongson.cn>
(cherry picked from commit fda2ad5e)

drivers/i2c/busses/Kconfig

@@ -866,6 +866,14 @@ config I2C_OWL
 	  Say Y here if you want to use the I2C bus controller on
 	  the Actions Semiconductor Owl SoC's.
 
+config I2C_LOONGSON
+	tristate "Loongson I2C adapter"
+	depends on LOONGARCH
+	default m
+	help
+	  If you say yes to this option, support will be included for the
+	  I2C interface on the Loongson's LS7A Platform-Bridge.
+
 config I2C_PASEMI
 	tristate "PA Semi SMBus interface"
 	depends on PPC_PASEMI && PCI

drivers/i2c/busses/Makefile

@@ -89,6 +89,7 @@ obj-$(CONFIG_I2C_NPCM7XX)	+= i2c-npcm7xx.o
 obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o
 obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o
 obj-$(CONFIG_I2C_OWL)		+= i2c-owl.o
+obj-$(CONFIG_I2C_LOONGSON)	+= i2c-loongson.o
 obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o
 obj-$(CONFIG_I2C_PCA_PLATFORM)	+= i2c-pca-platform.o
 obj-$(CONFIG_I2C_PMCMSP)	+= i2c-pmcmsp.o

drivers/i2c/busses/i2c-loongson.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Loongson-7A I2C master mode driver
+ *
+ * Copyright (C) 2013 Loongson Technology Corporation Limited
+ * Copyright (C) 2014-2017 Lemote, Inc.
+ *
+ */
+
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+#define DRIVER_NAME "loongson_i2c"
+
+#define LOONGSON_I2C_PRER_LO_REG	0x0
+#define LOONGSON_I2C_PRER_HI_REG	0x1
+#define LOONGSON_I2C_CTR_REG	0x2
+#define LOONGSON_I2C_TXR_REG	0x3
+#define LOONGSON_I2C_RXR_REG	0x3
+#define LOONGSON_I2C_CR_REG		0x4
+#define LOONGSON_I2C_SR_REG		0x4
+#define LOONGSON_I2C_BLTOP_REG	0x5
+#define LOONGSON_I2C_SADDR_REG	0x7
+
+#define CTR_EN			0x80
+#define CTR_IEN			0x40
+#define CTR_TXROK		0x90
+#define CTR_RXROK		0x88
+
+#define CR_START		0x81
+#define CR_STOP			0x41
+#define CR_READ			0x21
+#define CR_WRITE		0x11
+#define CR_ACK			0x8
+#define CR_IACK			0x1
+
+#define SR_NOACK		0x80
+#define SR_BUSY			0x40
+#define SR_AL			0x20
+#define SR_SLAVE_ADDRESSED	0x10
+#define SR_SLAVE_RW		0x8
+#define SR_TIP			0x2
+#define SR_IF			0x1
+
+#define i2c_readb(addr)		readb(dev->base + addr)
+#define i2c_writeb(val, addr)	writeb(val, dev->base + addr)
+
+#ifdef LOONGSON_I2C_DEBUG
+#define i2c_debug(fmt, args...)	printk(KERN_CRIT fmt, ##args)
+#else
+#define i2c_debug(fmt, args...)
+#endif
+
+static bool repeated_start = 1;
+module_param(repeated_start, bool, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(repeated_start, "Compatible with devices that support repeated start");
+
+enum loongson_i2c_slave_state {
+	LOONGSON_I2C_SLAVE_STOP,
+	LOONGSON_I2C_SLAVE_START,
+	LOONGSON_I2C_SLAVE_READ_REQUESTED,
+	LOONGSON_I2C_SLAVE_READ_PROCESSED,
+	LOONGSON_I2C_SLAVE_WRITE_REQUESTED,
+	LOONGSON_I2C_SLAVE_WRITE_RECEIVED,
+};
+
+struct loongson_i2c_dev {
+	spinlock_t		lock;
+	unsigned int		suspended:1;
+	struct device		*dev;
+	void __iomem		*base;
+	int			irq;
+	struct completion	cmd_complete;
+	struct resource		*ioarea;
+	struct i2c_adapter	adapter;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	struct i2c_client	*slave;
+	enum loongson_i2c_slave_state	slave_state;
+#endif /* CONFIG_I2C_SLAVE */
+};
+
+static int i2c_stop(struct loongson_i2c_dev *dev)
+{
+	unsigned long time_left;
+
+again:
+	i2c_writeb(CR_STOP, LOONGSON_I2C_CR_REG);
+	time_left = wait_for_completion_timeout(
+		&dev->cmd_complete,
+		(&dev->adapter)->timeout);
+	if (!time_left) {
+		pr_info("Timeout abort message cmd\n");
+		return -1;
+	}
+
+	i2c_readb(LOONGSON_I2C_SR_REG);
+	while (i2c_readb(LOONGSON_I2C_SR_REG) & SR_BUSY)
+		goto again;
+
+	return 0;
+}
+
+static int i2c_start(struct loongson_i2c_dev *dev,
+		int dev_addr, int flags)
+{
+	unsigned long time_left;
+	int retry = 5;
+	unsigned char addr = (dev_addr & 0x7f) << 1;
+	addr |= (flags & I2C_M_RD)? 1:0;
+
+start:
+	mdelay(1);
+	i2c_writeb(addr, LOONGSON_I2C_TXR_REG);
+	i2c_debug("%s <line%d>: i2c device address: 0x%x\n",
+			__func__, __LINE__, addr);
+	i2c_writeb((CR_START | CR_WRITE), LOONGSON_I2C_CR_REG);
+	time_left = wait_for_completion_timeout(
+		&dev->cmd_complete,
+		(&dev->adapter)->timeout);
+	if (!time_left) {
+		pr_info("Timeout abort message cmd\n");
+		return -1;
+	}
+
+	if (i2c_readb(LOONGSON_I2C_SR_REG) & SR_NOACK) {
+		if (i2c_stop(dev) < 0)
+			return -1;
+		while (retry--)
+			goto start;
+		pr_debug("There is no i2c device ack\n");
+		return 0;
+	}
+	return 1;
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static void __loongson_i2c_reg_slave(struct loongson_i2c_dev *dev, u16 slave_addr)
+{
+	/* Set slave addr. */
+	i2c_writeb(slave_addr & 0x7f, LOONGSON_I2C_SADDR_REG);
+
+	/* Turn on slave mode. */
+	i2c_writeb(0xc0, LOONGSON_I2C_CTR_REG);
+}
+
+static int loongson_i2c_reg_slave(struct i2c_client *client)
+{
+	struct loongson_i2c_dev *dev = i2c_get_adapdata(client->adapter);
+	unsigned long flags;
+
+	if (dev->slave) {
+		return -EINVAL;
+	}
+
+	__loongson_i2c_reg_slave(dev, client->addr);
+
+	dev->slave = client;
+	dev->slave_state = LOONGSON_I2C_SLAVE_STOP;
+
+	return 0;
+}
+
+static int loongson_i2c_unreg_slave(struct i2c_client *client)
+{
+	struct loongson_i2c_dev *dev = i2c_get_adapdata(client->adapter);
+	unsigned long flags;
+
+	if (!dev->slave) {
+		return -EINVAL;
+	}
+
+	/* Turn off slave mode. */
+	i2c_writeb(0xa0, LOONGSON_I2C_CTR_REG);
+
+	dev->slave = NULL;
+
+	return 0;
+}
+#endif /* CONFIG_I2C_SLAVE */
+
+static void loongson_i2c_reginit(struct loongson_i2c_dev *dev)
+{
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	if (dev->slave) {
+		__loongson_i2c_reg_slave(dev, dev->slave->addr);
+		return;
+	}
+#endif /* CONFIG_I2C_SLAVE */
+	i2c_writeb(i2c_readb(LOONGSON_I2C_CR_REG) | 0x01, LOONGSON_I2C_CR_REG);
+	i2c_writeb(i2c_readb(LOONGSON_I2C_CTR_REG) & ~0x80, LOONGSON_I2C_CTR_REG);
+	i2c_writeb(0x2c, LOONGSON_I2C_PRER_LO_REG);
+	i2c_writeb(0x1, LOONGSON_I2C_PRER_HI_REG);
+	i2c_writeb(i2c_readb(LOONGSON_I2C_CTR_REG) | 0xe0, LOONGSON_I2C_CTR_REG);
+}
+
+static int i2c_read(struct loongson_i2c_dev *dev,
+		unsigned char *buf, int count)
+{
+	int i;
+	unsigned long time_left;
+
+	for (i = 0; i < count; i++) {
+		i2c_writeb((i == count - 1)?
+				(CR_READ | CR_ACK) : CR_READ,
+				LOONGSON_I2C_CR_REG);
+		time_left = wait_for_completion_timeout(
+			&dev->cmd_complete,
+			(&dev->adapter)->timeout);
+		if (!time_left) {
+			pr_info("Timeout abort message cmd\n");
+			return -1;
+		}
+
+		buf[i] = i2c_readb(LOONGSON_I2C_RXR_REG);
+		i2c_debug("%s <line%d>: read buf[%d] <= %02x\n",
+				__func__, __LINE__, i, buf[i]);
+        }
+
+        return i;
+}
+
+static int i2c_write(struct loongson_i2c_dev *dev,
+		unsigned char *buf, int count)
+{
+        int i;
+	unsigned long time_left;
+
+        for (i = 0; i < count; i++) {
+		i2c_writeb(buf[i], LOONGSON_I2C_TXR_REG);
+		i2c_debug("%s <line%d>: write buf[%d] => %02x\n",
+				__func__, __LINE__, i, buf[i]);
+		i2c_writeb(CR_WRITE, LOONGSON_I2C_CR_REG);
+		time_left = wait_for_completion_timeout(
+			&dev->cmd_complete,
+			(&dev->adapter)->timeout);
+		if (!time_left) {
+			pr_info("Timeout abort message cmd\n");
+			return -1;
+		}
+
+		if (i2c_readb(LOONGSON_I2C_SR_REG) & SR_NOACK) {
+			i2c_debug("%s <line%d>: device no ack\n",
+					__func__, __LINE__);
+			if (i2c_stop(dev) < 0)
+				return -1;
+			return 0;
+		}
+        }
+
+        return i;
+}
+
+static int i2c_doxfer(struct loongson_i2c_dev *dev,
+		struct i2c_msg *msgs, int num)
+{
+	struct i2c_msg *m = msgs;
+	int i, err;
+
+	for (i = 0; i < num; i++) {
+		reinit_completion(&dev->cmd_complete);
+		err = i2c_start(dev, m->addr, m->flags);
+		if (err <= 0)
+			return err;
+
+		if (m->flags & I2C_M_RD) {
+			if (i2c_read(dev, m->buf, m->len) < 0)
+				return -1;
+		} else {
+			if (i2c_write(dev, m->buf, m->len) < 0)
+				return -1;
+		}
+		++m;
+		if (!repeated_start && i2c_stop(dev) < 0)
+			return -1;
+	}
+	if (repeated_start && i2c_stop(dev) < 0)
+		return -1;
+	return i;
+}
+
+static int i2c_xfer(struct i2c_adapter *adap,
+                        struct i2c_msg *msgs, int num)
+{
+	int ret;
+	int retry;
+	struct loongson_i2c_dev *dev;
+
+	dev = i2c_get_adapdata(adap);
+	for (retry = 0; retry < adap->retries; retry++) {
+		ret = i2c_doxfer(dev, msgs, num);
+		if (ret != -EAGAIN)
+			return ret;
+
+		udelay(100);
+	}
+
+	return -EREMOTEIO;
+}
+
+static unsigned int i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm loongson_i2c_algo = {
+	.master_xfer	= i2c_xfer,
+	.functionality	= i2c_func,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	.reg_slave	= loongson_i2c_reg_slave,
+	.unreg_slave	= loongson_i2c_unreg_slave,
+#endif /* CONFIG_I2C_SLAVE */
+};
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static bool loongson_i2c_slave_irq(struct loongson_i2c_dev *dev)
+{
+	u32 stat;
+	struct i2c_client *slave = dev->slave;
+	u8 value;
+
+	stat = i2c_readb(LOONGSON_I2C_SR_REG);
+
+	/* Slave was requested, restart state machine. */
+	if (stat & SR_SLAVE_ADDRESSED) {
+		dev->slave_state = LOONGSON_I2C_SLAVE_START;
+		i2c_writeb(CTR_RXROK | CTR_IEN, LOONGSON_I2C_CTR_REG);
+	}
+
+	/* Slave is not currently active, irq was for someone else. */
+	if (dev->slave_state == LOONGSON_I2C_SLAVE_STOP) {
+		return IRQ_NONE;
+	}
+
+	/* Handle address frame. */
+	if (dev->slave_state == LOONGSON_I2C_SLAVE_START) {
+		if (stat & SR_SLAVE_RW)	//slave be read
+			dev->slave_state =
+				LOONGSON_I2C_SLAVE_READ_REQUESTED;
+		else
+			dev->slave_state =
+				LOONGSON_I2C_SLAVE_WRITE_REQUESTED;
+	}
+
+	/* Slave was asked to stop. */
+	if (stat & SR_NOACK) {
+		dev->slave_state = LOONGSON_I2C_SLAVE_STOP;
+	}
+
+	value = i2c_readb(LOONGSON_I2C_RXR_REG);
+	switch (dev->slave_state) {
+	case LOONGSON_I2C_SLAVE_READ_REQUESTED:
+		dev->slave_state = LOONGSON_I2C_SLAVE_READ_PROCESSED;
+		i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
+		i2c_writeb(value, LOONGSON_I2C_TXR_REG);
+		i2c_writeb(CTR_TXROK | CTR_IEN, LOONGSON_I2C_CTR_REG);
+		break;
+	case LOONGSON_I2C_SLAVE_READ_PROCESSED:
+		i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
+		i2c_writeb(value, LOONGSON_I2C_TXR_REG);
+		i2c_writeb(CTR_TXROK | CTR_IEN, LOONGSON_I2C_CTR_REG);
+		break;
+	case LOONGSON_I2C_SLAVE_WRITE_REQUESTED:
+		dev->slave_state = LOONGSON_I2C_SLAVE_WRITE_RECEIVED;
+		i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+		break;
+	case LOONGSON_I2C_SLAVE_WRITE_RECEIVED:
+		i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
+		i2c_writeb(CTR_RXROK | CTR_IEN, LOONGSON_I2C_CTR_REG);
+		break;
+	case LOONGSON_I2C_SLAVE_STOP:
+		i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
+		i2c_writeb(0, LOONGSON_I2C_TXR_REG);
+		i2c_writeb(CTR_TXROK | CTR_IEN, LOONGSON_I2C_CTR_REG);
+		break;
+	default:
+		dev_err(dev->dev, "unhandled slave_state: %d\n",
+			dev->slave_state);
+		break;
+	}
+
+out:
+	return IRQ_HANDLED;
+}
+#endif /* CONFIG_I2C_SLAVE */
+
+/*
+ * Interrupt service routine. This gets called whenever an I2C interrupt
+ * occurs.
+ */
+static irqreturn_t i2c_loongson_isr(int this_irq, void *dev_id)
+{
+	unsigned char iflag;
+	struct loongson_i2c_dev *dev = dev_id;
+
+	iflag = i2c_readb(LOONGSON_I2C_SR_REG);
+
+	if (iflag & SR_IF) {
+		i2c_writeb(CR_IACK, LOONGSON_I2C_CR_REG);
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+		if (dev->slave) {
+			loongson_i2c_slave_irq(dev);
+		}
+#endif
+		if (!(iflag & SR_TIP))
+			complete(&dev->cmd_complete);
+	} else
+		return IRQ_NONE;
+
+	return IRQ_HANDLED;
+}
+
+static int loongson_i2c_probe(struct platform_device *pdev)
+{
+	struct loongson_i2c_dev	*dev;
+	struct i2c_adapter	*adap;
+	struct resource		*mem, *ioarea;
+	int r, irq;
+
+	/* NOTE: driver uses the static register mapping */
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem) {
+		dev_err(&pdev->dev, "no mem resource?\n");
+		return -ENODEV;
+	}
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0) {
+		dev_err(&pdev->dev, "no irq resource?\n");
+		return -ENODEV;
+	}
+
+	ioarea = request_mem_region(mem->start, resource_size(mem),
+			pdev->name);
+	if (!ioarea) {
+		dev_err(&pdev->dev, "I2C region already claimed\n");
+		return -EBUSY;
+	}
+
+	dev = kzalloc(sizeof(struct loongson_i2c_dev), GFP_KERNEL);
+	if (!dev) {
+		r = -ENOMEM;
+		goto err_release_region;
+	}
+
+	init_completion(&dev->cmd_complete);
+
+	dev->dev = &pdev->dev;
+	dev->irq = irq;
+	dev->base = ioremap(mem->start, resource_size(mem));
+	if (!dev->base) {
+		r = -ENOMEM;
+		goto err_free_mem;
+	}
+
+	platform_set_drvdata(pdev, dev);
+
+	loongson_i2c_reginit(dev);
+
+	r = request_irq(dev->irq, i2c_loongson_isr, IRQF_SHARED, DRIVER_NAME, dev);
+	if (r)
+		dev_err(&pdev->dev, "failure requesting irq %i\n", dev->irq);
+
+	adap = &dev->adapter;
+	i2c_set_adapdata(adap, dev);
+	adap->nr = pdev->id;
+	strlcpy(adap->name, pdev->name, sizeof(adap->name));
+	adap->owner = THIS_MODULE;
+	adap->class = I2C_CLASS_HWMON;
+	adap->retries = 5;
+	adap->algo = &loongson_i2c_algo;
+	adap->dev.parent = &pdev->dev;
+	adap->dev.of_node = pdev->dev.of_node;
+	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
+	adap->timeout = msecs_to_jiffies(100);
+
+	/* i2c device drivers may be active on return from add_adapter() */
+	r = i2c_add_adapter(adap);
+	if (r) {
+		dev_err(dev->dev, "failure adding adapter\n");
+		goto err_iounmap;
+	}
+
+	return 0;
+
+err_iounmap:
+	iounmap(dev->base);
+err_free_mem:
+	platform_set_drvdata(pdev, NULL);
+	kfree(dev);
+err_release_region:
+	release_mem_region(mem->start, resource_size(mem));
+
+	return r;
+}
+
+static int loongson_i2c_remove(struct platform_device *pdev)
+{
+	struct loongson_i2c_dev	*dev = platform_get_drvdata(pdev);
+	struct resource		*mem;
+
+	platform_set_drvdata(pdev, NULL);
+	i2c_del_adapter(&dev->adapter);
+	iounmap(dev->base);
+	kfree(dev);
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(mem->start, resource_size(mem));
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int loongson_i2c_suspend_noirq(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct loongson_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+
+	i2c_dev->suspended = 1;
+
+	return 0;
+}
+
+static int loongson_i2c_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct loongson_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+
+	i2c_dev->suspended = 0;
+	loongson_i2c_reginit(i2c_dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops loongson_i2c_dev_pm_ops = {
+	.suspend_noirq	= loongson_i2c_suspend_noirq,
+	.resume		= loongson_i2c_resume,
+};
+
+#define LOONGSON_DEV_PM_OPS (&loongson_i2c_dev_pm_ops)
+#else
+#define LOONGSON_DEV_PM_OPS NULL
+#endif
+
+#ifdef CONFIG_OF
+static struct of_device_id loongson_i2c_id_table[] = {
+	{.compatible = "loongson,ls7a-i2c"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, loongson_i2c_id_table);
+#endif
+static const struct acpi_device_id loongson_i2c_acpi_match[] = {
+	{"LOON0004"},
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, loongson_i2c_acpi_match);
+
+static struct platform_driver loongson_i2c_driver = {
+	.probe		= loongson_i2c_probe,
+	.remove		= loongson_i2c_remove,
+	.driver		= {
+		.name	= "loongson-i2c",
+		.owner	= THIS_MODULE,
+		.pm	= LOONGSON_DEV_PM_OPS,
+#ifdef CONFIG_OF
+		.of_match_table = of_match_ptr(loongson_i2c_id_table),
+#endif
+		.acpi_match_table = ACPI_PTR(loongson_i2c_acpi_match),
+	},
+};
+
+static int __init loongson_i2c_init_driver(void)
+{
+	return platform_driver_register(&loongson_i2c_driver);
+}
+subsys_initcall(loongson_i2c_init_driver);
+
+static void __exit loongson_i2c_exit_driver(void)
+{
+	platform_driver_unregister(&loongson_i2c_driver);
+}
+module_exit(loongson_i2c_exit_driver);
+
+MODULE_AUTHOR("Loongson Technology Corporation Limited");
+MODULE_DESCRIPTION("Loongson LOONGSON I2C bus adapter");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:loongson-i2c");