soc: aspeed: add lpc mbox driver

This commit adds back the lpc mbox driver which was removed from
the openbmc linux dev-5.2 tree.

This driver should be rewritten later.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
Signed-off-by: Arun P. Mohanan <arun.p.m@linux.intel.com>

6 files changed, 407 insertions, 0 deletions

diff --git a/arch/arm/boot/dts/aspeed-g4.dtsi b/arch/arm/boot/dts/aspeed-g4.dtsi
index a0855403eb46..524399a38933 100644
--- a/arch/arm/boot/dts/aspeed-g4.dtsi
+++ b/arch/arm/boot/dts/aspeed-g4.dtsi
@@ -389,6 +389,15 @@
 					reg = <0x9c 0x4>;
 					status = "disabled";
 				};
+
+				mbox: mbox@200 {
+					compatible = "aspeed,ast2400-mbox";
+					reg = <0x200 0x5c>;
+					interrupts = <46>;
+					#mbox-cells = <1>;
+					clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
+					status = "disabled";
+				};
 			};
 
 			peci: bus@1e78b000 {
diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
index ab300c56fc10..b5149cf1e12c 100644
--- a/arch/arm/boot/dts/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed-g5.dtsi
@@ -516,6 +516,15 @@
 					interrupts = <8>;
 					status = "disabled";
 				};
+
+				mbox: mbox@200 {
+					compatible = "aspeed,ast2500-mbox";
+					reg = <0x200 0x5c>;
+					interrupts = <46>;
+					#mbox-cells = <1>;
+					clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
+					status = "disabled";
+				};
 			};
 
 			peci: bus@1e78b000 {
diff --git a/arch/arm/boot/dts/aspeed-g6.dtsi b/arch/arm/boot/dts/aspeed-g6.dtsi
index b121871cefbe..b1b4b534f41d 100644
--- a/arch/arm/boot/dts/aspeed-g6.dtsi
+++ b/arch/arm/boot/dts/aspeed-g6.dtsi
@@ -604,6 +604,13 @@
 					status = "disabled";
 				};
 
+				mbox: mbox@200 {
+					compatible = "aspeed,ast2600-mbox";
+					reg = <0x200 0x5c>;
+					interrupts = <GIC_SPI 54 IRQ_TYPE_LEVEL_HIGH>;
+					#mbox-cells = <1>;
+					clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
+				};
 			};
 
 			sdc: sdc@1e740000 {
diff --git a/drivers/soc/aspeed/Kconfig b/drivers/soc/aspeed/Kconfig
index f941c41b84dc..40b19ff197e1 100644
--- a/drivers/soc/aspeed/Kconfig
+++ b/drivers/soc/aspeed/Kconfig
@@ -14,6 +14,13 @@ config ASPEED_LPC_CTRL
 	  also provides a read/write interface to a BMC ram region where the
 	  host LPC read/write region can be buffered.
 
+config ASPEED_LPC_MBOX
+	tristate "Aspeed LPC Mailbox Controller"
+	depends on REGMAP && MFD_SYSCON
+	help
+	  Expose the ASPEED LPC MBOX registers found on Aspeed SOCs (AST2400
+	  and AST2500) to userspace.
+
 config ASPEED_LPC_SNOOP
 	tristate "ASPEED LPC snoop support"
 	select REGMAP
diff --git a/drivers/soc/aspeed/Makefile b/drivers/soc/aspeed/Makefile
index 8fb73cede4bf..222f8e6aa498 100644
--- a/drivers/soc/aspeed/Makefile
+++ b/drivers/soc/aspeed/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_ASPEED_LPC_CTRL)		+= aspeed-lpc-ctrl.o
+obj-$(CONFIG_ASPEED_LPC_MBOX)		+= aspeed-lpc-mbox.o
 obj-$(CONFIG_ASPEED_LPC_SNOOP)		+= aspeed-lpc-snoop.o
 obj-$(CONFIG_ASPEED_UART_ROUTING)	+= aspeed-uart-routing.o
 obj-$(CONFIG_ASPEED_P2A_CTRL)		+= aspeed-p2a-ctrl.o
diff --git a/drivers/soc/aspeed/aspeed-lpc-mbox.c b/drivers/soc/aspeed/aspeed-lpc-mbox.c
new file mode 100644
index 000000000000..5e45777c13ac
--- /dev/null
+++ b/drivers/soc/aspeed/aspeed-lpc-mbox.c
@@ -0,0 +1,374 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright 2017 IBM Corporation
+// TODO: Rewrite this driver
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/poll.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define DEVICE_NAME	"aspeed-mbox"
+
+#define MBX_USE_INTERRUPT 0
+
+#define ASPEED_MBOX_NUM_REGS 16
+
+#define ASPEED_MBOX_DATA_0 0x00
+#define ASPEED_MBOX_STATUS_0 0x40
+#define ASPEED_MBOX_STATUS_1 0x44
+#define ASPEED_MBOX_BMC_CTRL 0x48
+#define   ASPEED_MBOX_CTRL_RECV BIT(7)
+#define   ASPEED_MBOX_CTRL_MASK BIT(1)
+#define   ASPEED_MBOX_CTRL_SEND BIT(0)
+#define ASPEED_MBOX_HOST_CTRL 0x4c
+#define ASPEED_MBOX_INTERRUPT_0 0x50
+#define ASPEED_MBOX_INTERRUPT_1 0x54
+
+struct aspeed_mbox {
+	struct miscdevice	miscdev;
+	struct regmap		*regmap;
+	struct clk		*clk;
+	unsigned int		base;
+	int			irq;
+	wait_queue_head_t	queue;
+	struct mutex		mutex;
+};
+
+static atomic_t aspeed_mbox_open_count = ATOMIC_INIT(0);
+
+static u8 aspeed_mbox_inb(struct aspeed_mbox *mbox, int reg)
+{
+	/*
+	 * The mbox registers are actually only one byte but are addressed
+	 * four bytes apart. The other three bytes are marked 'reserved',
+	 * they *should* be zero but lets not rely on it.
+	 * I am going to rely on the fact we can casually read/write to them...
+	 */
+	unsigned int val = 0xff; /* If regmap throws an error return 0xff */
+	int rc = regmap_read(mbox->regmap, mbox->base + reg, &val);
+
+	if (rc)
+		dev_err(mbox->miscdev.parent, "regmap_read() failed with "
+				"%d (reg: 0x%08x)\n", rc, reg);
+
+	return val & 0xff;
+}
+
+static void aspeed_mbox_outb(struct aspeed_mbox *mbox, u8 data, int reg)
+{
+	int rc = regmap_write(mbox->regmap, mbox->base + reg, data);
+
+	if (rc)
+		dev_err(mbox->miscdev.parent, "regmap_write() failed with "
+				"%d (data: %u reg: 0x%08x)\n", rc, data, reg);
+}
+
+static struct aspeed_mbox *file_mbox(struct file *file)
+{
+	return container_of(file->private_data, struct aspeed_mbox, miscdev);
+}
+
+static int aspeed_mbox_open(struct inode *inode, struct file *file)
+{
+#if MBX_USE_INTERRUPT
+	struct aspeed_mbox *mbox = file_mbox(file);
+#endif
+
+	if (atomic_inc_return(&aspeed_mbox_open_count) == 1) {
+#if MBX_USE_INTERRUPT
+		/*
+		 * Clear the interrupt status bit if it was left on and unmask
+		 * interrupts.
+		 * ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step
+		 */
+		aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
+#endif
+		return 0;
+	}
+
+	atomic_dec(&aspeed_mbox_open_count);
+	return -EBUSY;
+}
+
+static ssize_t aspeed_mbox_read(struct file *file, char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	struct aspeed_mbox *mbox = file_mbox(file);
+	char __user *p = buf;
+	ssize_t ret;
+	int i;
+
+	if (!access_ok(buf, count))
+		return -EFAULT;
+
+	if (count + *ppos > ASPEED_MBOX_NUM_REGS)
+		return -EINVAL;
+
+#if MBX_USE_INTERRUPT
+	if (file->f_flags & O_NONBLOCK) {
+		if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
+				ASPEED_MBOX_CTRL_RECV))
+			return -EAGAIN;
+	} else if (wait_event_interruptible(mbox->queue,
+				aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
+				ASPEED_MBOX_CTRL_RECV)) {
+		return -ERESTARTSYS;
+	}
+#endif
+
+	mutex_lock(&mbox->mutex);
+
+	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
+		uint8_t reg = aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4));
+
+		ret = __put_user(reg, p);
+		if (ret)
+			goto out_unlock;
+
+		p++;
+		count--;
+	}
+
+#if MBX_USE_INTERRUPT
+	/* ASPEED_MBOX_CTRL_RECV bit is write to clear, this also unmasks in 1 step */
+	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
+#endif
+	ret = p - buf;
+
+out_unlock:
+	mutex_unlock(&mbox->mutex);
+	return ret;
+}
+
+static ssize_t aspeed_mbox_write(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	struct aspeed_mbox *mbox = file_mbox(file);
+	const char __user *p = buf;
+	ssize_t ret;
+	char c;
+	int i;
+
+	if (!access_ok(buf, count))
+		return -EFAULT;
+
+	if (count + *ppos > ASPEED_MBOX_NUM_REGS)
+		return -EINVAL;
+
+	mutex_lock(&mbox->mutex);
+
+	for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
+		ret = __get_user(c, p);
+		if (ret)
+			goto out_unlock;
+
+		aspeed_mbox_outb(mbox, c, ASPEED_MBOX_DATA_0 + (i * 4));
+		p++;
+		count--;
+	}
+
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_0);
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_1);
+	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV | ASPEED_MBOX_CTRL_MASK | ASPEED_MBOX_CTRL_SEND, ASPEED_MBOX_BMC_CTRL);
+	ret = p - buf;
+
+out_unlock:
+	mutex_unlock(&mbox->mutex);
+	return ret;
+}
+
+static unsigned int aspeed_mbox_poll(struct file *file, poll_table *wait)
+{
+	struct aspeed_mbox *mbox = file_mbox(file);
+	unsigned int mask = 0;
+
+	poll_wait(file, &mbox->queue, wait);
+
+#if MBX_USE_INTERRUPT
+	if (aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_MBOX_CTRL_RECV)
+#endif
+		mask |= POLLIN;
+
+	return mask;
+}
+
+static int aspeed_mbox_release(struct inode *inode, struct file *file)
+{
+	atomic_dec(&aspeed_mbox_open_count);
+	return 0;
+}
+
+static const struct file_operations aspeed_mbox_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_seek_end_llseek,
+	.read		= aspeed_mbox_read,
+	.write		= aspeed_mbox_write,
+	.open		= aspeed_mbox_open,
+	.release	= aspeed_mbox_release,
+	.poll		= aspeed_mbox_poll,
+};
+
+static irqreturn_t aspeed_mbox_irq(int irq, void *arg)
+{
+	struct aspeed_mbox *mbox = arg;
+#if MBX_USE_INTERRUPT
+	int i;
+
+//	if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) & ASPEED_MBOX_CTRL_RECV))
+//		return IRQ_NONE;
+
+	printk(KERN_ERR "BMC_CTRL: 0x%02x\n",
+	       aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL));
+	printk(KERN_ERR "STATUS_0: 0x%02x\n",
+	       aspeed_mbox_inb(mbox, ASPEED_MBOX_STATUS_0));
+	printk(KERN_ERR "STATUS_1: 0x%02x\n",
+	       aspeed_mbox_inb(mbox, ASPEED_MBOX_STATUS_1));
+	for (i = 0; i < ASPEED_MBOX_NUM_REGS; i++) {
+		printk(KERN_ERR "DATA_%d: 0x%02x\n", i,
+		       aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4)));
+	}
+#endif
+
+	/* Clear interrupt status */
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_0);
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_1);
+	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
+
+	wake_up(&mbox->queue);
+	return IRQ_HANDLED;
+}
+
+static int aspeed_mbox_config_irq(struct aspeed_mbox *mbox,
+		struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	int rc;
+
+	mbox->irq = platform_get_irq(pdev, 0);
+	if (!mbox->irq)
+		return -ENODEV;
+
+	rc = devm_request_irq(dev, mbox->irq, aspeed_mbox_irq,
+			      IRQF_SHARED, DEVICE_NAME, mbox);
+	if (rc < 0) {
+		dev_err(dev, "Unable to request IRQ %d\n", mbox->irq);
+		return rc;
+	}
+
+	/* Disable all register based interrupts. */
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_INTERRUPT_0); /* regs 0 - 7 */
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_INTERRUPT_1); /* regs 8 - 15 */
+
+	/* These registers are write one to clear. Clear them. */
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_0);
+	aspeed_mbox_outb(mbox, 0xff, ASPEED_MBOX_STATUS_1);
+
+	aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
+	return 0;
+}
+
+static int aspeed_mbox_probe(struct platform_device *pdev)
+{
+	struct aspeed_mbox *mbox;
+	struct device *dev;
+	int rc;
+
+	dev = &pdev->dev;
+
+	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
+	if (!mbox)
+		return -ENOMEM;
+
+	dev_set_drvdata(&pdev->dev, mbox);
+
+	rc = of_property_read_u32(dev->of_node, "reg", &mbox->base);
+	if (rc) {
+		dev_err(dev, "Couldn't read reg device-tree property\n");
+		return rc;
+	}
+
+	mbox->regmap = syscon_node_to_regmap(
+			pdev->dev.parent->of_node);
+	if (IS_ERR(mbox->regmap)) {
+		dev_err(dev, "Couldn't get regmap\n");
+		return -ENODEV;
+	}
+
+	mutex_init(&mbox->mutex);
+	init_waitqueue_head(&mbox->queue);
+
+	mbox->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(mbox->clk))
+		return dev_err_probe(dev, PTR_ERR(mbox->clk),
+				     "couldn't get clock\n");
+	rc = clk_prepare_enable(mbox->clk);
+	if (rc) {
+		dev_err(dev, "couldn't enable clock\n");
+		return rc;
+	}
+
+	mbox->miscdev.minor = MISC_DYNAMIC_MINOR;
+	mbox->miscdev.name = DEVICE_NAME;
+	mbox->miscdev.fops = &aspeed_mbox_fops;
+	mbox->miscdev.parent = dev;
+	rc = misc_register(&mbox->miscdev);
+	if (rc) {
+		dev_err(dev, "Unable to register device\n");
+		goto err;
+	}
+
+	rc = aspeed_mbox_config_irq(mbox, pdev);
+	if (rc) {
+		dev_err(dev, "Failed to configure IRQ\n");
+		misc_deregister(&mbox->miscdev);
+		goto err;
+	}
+
+	dev_info(&pdev->dev, "LPC mbox registered, irq %d\n", mbox->irq);
+
+	return 0;
+
+err:
+	clk_disable_unprepare(mbox->clk);
+
+	return rc;
+}
+
+static int aspeed_mbox_remove(struct platform_device *pdev)
+{
+	struct aspeed_mbox *mbox = dev_get_drvdata(&pdev->dev);
+
+	misc_deregister(&mbox->miscdev);
+	clk_disable_unprepare(mbox->clk);
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_mbox_match[] = {
+	{ .compatible = "aspeed,ast2400-mbox" },
+	{ .compatible = "aspeed,ast2500-mbox" },
+	{ .compatible = "aspeed,ast2600-mbox" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, aspeed_mbox_match);
+
+static struct platform_driver aspeed_mbox_driver = {
+	.driver = {
+		.name		= DEVICE_NAME,
+		.of_match_table = aspeed_mbox_match,
+	},
+	.probe = aspeed_mbox_probe,
+	.remove = aspeed_mbox_remove,
+};
+
+module_platform_driver(aspeed_mbox_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Cyril Bur <cyrilbur@gmail.com>");
+MODULE_DESCRIPTION("Aspeed mailbox device driver");