bt/ipmi: Add Aspeed BT IPMI host driver

This patch adds a simple device driver to expose the iBT interface on
Aspeed chips as a character device (/dev/bt).

Signed-off-by: Alistair Popple <alistair@popple.id.au>

4 files changed, 396 insertions, 0 deletions

diff --git a/arch/arm/boot/dts/aspeed-bmc-opp-palmetto.dts b/arch/arm/boot/dts/aspeed-bmc-opp-palmetto.dts
index ff2ce3b93d24..2fb6082214ce 100644
--- a/arch/arm/boot/dts/aspeed-bmc-opp-palmetto.dts
+++ b/arch/arm/boot/dts/aspeed-bmc-opp-palmetto.dts
@@ -85,6 +85,11 @@
 				reg = <0x1e72000 0x8000>;	// 32K
 			};
 
+			ibt@1e789150 {
+				compatible = "bt-host";
+				reg = <0x1e789140 0x18>;
+			};
+
 			i2c0: i2c@1e78a040 {
 				compatible = "aspeed,ast2400-i2c", "i2c";
 				reg = <0x1e78a040 0x40>, <0x1e78a000 0x40>;
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 42c38525904b..a5553af7ed0f 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -515,6 +515,11 @@ config VEXPRESS_SYSCFG
 	  bus. System Configuration interface is one of the possible means
 	  of generating transactions on this bus.
 
+config ASPEED_BT_IPMI_HOST
+	tristate "BT IPMI host driver"
+	help
+	  Support for the Aspeed BT ipmi host.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index d056fb7186fe..eca67445ed21 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_GENWQE)		+= genwqe/
 obj-$(CONFIG_ECHO)		+= echo/
 obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
+obj-$(CONFIG_ASPEED_BT_IPMI_HOST)	+= bt-host.o
diff --git a/drivers/misc/bt-host.c b/drivers/misc/bt-host.c
new file mode 100644
index 000000000000..1f6e1c49b4af
--- /dev/null
+++ b/drivers/misc/bt-host.c
@@ -0,0 +1,385 @@
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/errno.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/cdev.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/miscdevice.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+
+#define DEVICE_NAME	"bt"
+#define BT_NUM_DEVS	1
+
+#define BT_IO_BASE	0xe4
+#define BT_IRQ		10
+
+#define BT_CR0		0x0
+#define   BT_CR0_IO_BASE		16
+#define   BT_CR0_IRQ			12
+#define   BT_CR0_EN_CLR_SLV_RDP		0x8
+#define   BT_CR0_EN_CLR_SLV_WRP		0x4
+#define   BT_CR0_ENABLE_IBT		0x1
+#define BT_CR1		0x4
+#define BT_CR2		0x8
+#define BT_CR3		0xc
+#define BT_CTRL		0x10
+#define   BT_CTRL_B_BUSY		0x80
+#define   BT_CTRL_H_BUSY		0x40
+#define   BT_CTRL_OEM0			0x20
+#define   BT_CTRL_SMS_ATN		0x10
+#define   BT_CTRL_B2H_ATN		0x08
+#define   BT_CTRL_H2B_ATN		0x04
+#define   BT_CTRL_CLR_RD_PTR		0x02
+#define   BT_CTRL_CLR_WR_PTR		0x01
+#define BT_BMC2HOST	0x14
+#define BT_INTMASK	0x18
+#define   BT_INTMASK_B2H_IRQEN		0x01
+#define   BT_INTMASK_B2H_IRQ		0x02
+#define   BT_INTMASK_BMC_HWRST		0x80
+
+dev_t bt_host_devt;
+
+struct bt_host {
+	struct device dev;
+	struct cdev cdev;
+	void *base;
+	int open_count;
+	wait_queue_head_t queue;
+	unsigned int ctrl;
+	struct timer_list poll_timer;
+};
+
+static struct bt_host *bt_host;
+
+static char bt_inb(struct bt_host *bt_host, int reg)
+{
+	return ioread8(bt_host->base + reg);
+}
+
+static void bt_outb(struct bt_host *bt_host, char data, int reg)
+{
+	iowrite8(data, bt_host->base + reg);
+}
+
+static void clr_rd_ptr(struct bt_host *bt_host)
+{
+	bt_outb(bt_host, BT_CTRL_CLR_RD_PTR, BT_CTRL);
+}
+
+static void clr_wr_ptr(struct bt_host *bt_host)
+{
+	bt_outb(bt_host, BT_CTRL_CLR_WR_PTR, BT_CTRL);
+}
+
+static int h2b_atn(struct bt_host *bt_host)
+{
+	return !!(bt_inb(bt_host, BT_CTRL) & BT_CTRL_H2B_ATN);
+}
+
+static void clr_h2b_atn(struct bt_host *bt_host)
+{
+	bt_outb(bt_host, BT_CTRL_H2B_ATN, BT_CTRL);
+}
+
+static void set_b_busy(struct bt_host *bt_host)
+{
+	if (!(bt_inb(bt_host, BT_CTRL) & BT_CTRL_B_BUSY))
+		bt_outb(bt_host, BT_CTRL_B_BUSY, BT_CTRL);}
+
+static void clr_b_busy(struct bt_host *bt_host)
+{
+	if (bt_inb(bt_host, BT_CTRL) & BT_CTRL_B_BUSY)
+		bt_outb(bt_host, BT_CTRL_B_BUSY, BT_CTRL);
+}
+
+static void set_b2h_atn(struct bt_host *bt_host)
+{
+	bt_outb(bt_host, BT_CTRL_B2H_ATN, BT_CTRL);
+}
+
+static int b2h_atn(struct bt_host *bt_host)
+{
+	return !!(bt_inb(bt_host, BT_CTRL) & BT_CTRL_B2H_ATN);
+}
+
+static int h_busy(struct bt_host *bt_host)
+{
+	return !!(bt_inb(bt_host, BT_CTRL) & BT_CTRL_H_BUSY);
+}
+
+static char bt_read(struct bt_host *bt_host)
+{
+	char result = bt_inb(bt_host, BT_BMC2HOST);
+
+	return result;
+}
+
+static void bt_write(struct bt_host *bt_host, char c)
+{
+	bt_outb(bt_host, c, BT_BMC2HOST);
+}
+
+static int bt_host_open(struct inode *inode, struct file *file)
+{
+	file->private_data = bt_host;
+
+	clr_b_busy(bt_host);
+
+	return 0;
+}
+
+static ssize_t bt_host_read(struct file *file, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	char __user *p = buf;
+	char len;
+
+	if (!access_ok(VERIFY_WRITE, buf, count))
+		return -EFAULT;
+
+	WARN_ON(*ppos);
+
+	if (wait_event_interruptible(bt_host->queue,
+				     bt_inb(bt_host, BT_CTRL)
+				     & BT_CTRL_H2B_ATN))
+		return -ERESTARTSYS;
+
+	set_b_busy(bt_host);
+	clr_h2b_atn(bt_host);
+	clr_rd_ptr(bt_host);
+
+	len = bt_read(bt_host);
+	__put_user(len, p++);
+
+	/* We pass the length back as well */
+	if (len + 1 > count)
+		len = count - 1;
+
+	while(len) {
+		if (__put_user(bt_read(bt_host), p))
+			return -EFAULT;
+		len--; p++;
+	}
+
+	clr_b_busy(bt_host);
+
+	return p - buf;
+}
+
+static ssize_t bt_host_write(struct file *file, const char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	const char __user *p = buf;
+	char c;
+
+	if (!access_ok(VERIFY_READ, buf, count))
+		return -EFAULT;
+
+	WARN_ON(*ppos);
+
+	/* There's no interrupt for clearing host busy so we have to
+	 * poll */
+	if (wait_event_interruptible(bt_host->queue,
+				     !(bt_inb(bt_host, BT_CTRL) &
+				       (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))))
+	    return -ERESTARTSYS;
+
+	clr_wr_ptr(bt_host);
+
+	while (count) {
+		if (__get_user(c, p))
+			return -EFAULT;
+
+		bt_write(bt_host, c);
+		count--; p++;
+	}
+
+	set_b2h_atn(bt_host);
+
+	return p - buf;
+}
+
+static int bt_host_release(struct inode *inode, struct file *file)
+{
+       set_b_busy(bt_host);
+
+       return 0;
+}
+
+static unsigned int bt_host_poll(struct file *file, poll_table *wait)
+{
+	uint8_t ctrl = bt_inb(bt_host, BT_CTRL);
+	unsigned int mask = 0;
+
+	poll_wait(file, &bt_host->queue, wait);
+
+	if (ctrl & BT_CTRL_H2B_ATN)
+		mask |= POLLIN;
+
+	if (!(ctrl & (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN)))
+		mask |= POLLOUT;
+
+	return mask;
+}
+
+static const struct file_operations bt_host_fops = {
+	.owner		= THIS_MODULE,
+	.open		= bt_host_open,
+	.read		= bt_host_read,
+	.write		= bt_host_write,
+	.release	= bt_host_release,
+	.poll		= bt_host_poll,
+};
+
+static struct miscdevice bt_host_miscdev = {
+	.minor		= MISC_DYNAMIC_MINOR,
+	.name		= "bt",
+	.fops  		= &bt_host_fops,
+};
+
+static void poll_timer(unsigned long data)
+{
+	bt_host->ctrl = bt_inb(bt_host, BT_CTRL);
+	bt_host->poll_timer.expires += msecs_to_jiffies(500);
+	wake_up(&bt_host->queue);
+	add_timer(&bt_host->poll_timer);
+}
+
+static int bt_host_probe(struct platform_device *pdev)
+{
+	struct device *dev;
+	struct resource *res;
+	int rc, devno = MKDEV(MAJOR(bt_host_devt), 0);
+
+	if (!pdev || !pdev->dev.of_node)
+		return -ENODEV;
+
+	dev = &pdev->dev;
+	dev_info(dev, "Found bt host device\n");
+
+	if (bt_host) {
+		dev_err(dev, "Multiple bt hosts not supported\n");
+		return -ENOMEM;
+	}
+
+	bt_host = devm_kzalloc(dev, sizeof(*bt_host), GFP_KERNEL);
+	if (!bt_host)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "Unable to find resources\n");
+		rc = -ENXIO;
+		goto out_free;
+	}
+
+	bt_host->base = devm_ioremap_nocache(&pdev->dev, res->start,
+					     resource_size(res));
+	if (!bt_host->base) {
+		rc = -ENOMEM;
+		goto out_free;
+	}
+
+	init_waitqueue_head(&bt_host->queue);
+
+	bt_host_miscdev.parent = dev;
+	rc = misc_register(&bt_host_miscdev);
+	if (rc) {
+		dev_err(dev, "Unable to register device\n");
+		goto out_unmap;
+	}
+
+	init_timer(&bt_host->poll_timer);
+	bt_host->poll_timer.function = poll_timer;
+	bt_host->poll_timer.expires = jiffies + msecs_to_jiffies(10);
+	add_timer(&bt_host->poll_timer);
+
+	iowrite32((BT_IO_BASE << BT_CR0_IO_BASE) |
+		  (BT_IRQ << BT_CR0_IRQ) |
+		  BT_CR0_EN_CLR_SLV_RDP |
+		  BT_CR0_EN_CLR_SLV_WRP |
+		  BT_CR0_ENABLE_IBT,
+		  bt_host->base + BT_CR0);
+	
+	clr_b_busy(bt_host);
+
+	return 0;
+
+out_unmap:
+	devm_iounmap(&pdev->dev, bt_host->base);
+
+out_free:
+	devm_kfree(dev, bt_host);
+	return rc;
+
+}
+
+static int bt_host_remove(struct platform_device *pdev)
+{
+	del_timer_sync(&bt_host->poll_timer);
+	misc_deregister(&bt_host_miscdev);
+	devm_iounmap(&pdev->dev, bt_host->base);
+	devm_kfree(&pdev->dev, bt_host);
+	bt_host = NULL;
+
+	return 0;
+}
+
+static const struct of_device_id bt_host_match[] = {
+	{ .compatible = "bt-host" },
+	{ },
+};
+
+static struct platform_driver bt_host_driver = {
+	.driver = {
+		.name		= "bt-host",
+		.owner		= THIS_MODULE,
+		.of_match_table = bt_host_match,
+	},
+	.probe = bt_host_probe,
+	.remove = bt_host_remove,
+};
+
+static int __init bt_host_init(void)
+{
+	int rc;
+
+	rc = alloc_chrdev_region(&bt_host_devt, 0, BT_NUM_DEVS, "bt");
+	if (rc) {
+		pr_err("bt-host: Could not allocate chardev region\n");
+		return rc;
+	}
+
+	rc = platform_driver_register(&bt_host_driver);
+	if (rc) {
+		pr_err("bt-host: Could not register platform device\n");
+		goto out_chardev;
+	}
+
+	return 0;
+
+out_chardev:
+	unregister_chrdev_region(bt_host_devt, BT_NUM_DEVS);
+	return rc;
+}
+module_init(bt_host_init);
+
+static void __exit bt_host_exit(void)
+{
+	platform_driver_unregister(&bt_host_driver);
+}
+module_exit(bt_host_exit);
+
+MODULE_DEVICE_TABLE(of, bt_host_match);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Alistair Popple <alistair@popple.id.au>");
+MODULE_DESCRIPTION("Linux device interface to the BT interface");