misc: bcm-vk: add ttyVK support

Add ttyVK support to driver to allow console access to VK card from host.

Device node will be in the follow form /dev/bcm-vk.x_ttyVKy where:
x is the instance of the VK card
y is the tty device number on the VK card

Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-14-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: sbranden

drivers/misc/bcm-vk/Makefile

@@ -7,5 +7,6 @@ obj-$(CONFIG_BCM_VK) += bcm_vk.o
 bcm_vk-objs := \
 	bcm_vk_dev.o \
 	bcm_vk_msg.o \
-	bcm_vk_sg.o
+	bcm_vk_sg.o \
+	bcm_vk_tty.o
 

drivers/misc/bcm-vk/bcm_vk.h

@@ -8,12 +8,14 @@
 
 #include <linux/atomic.h>
 #include <linux/firmware.h>
+#include <linux/irq.h>
 #include <linux/kref.h>
 #include <linux/miscdevice.h>
 #include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/poll.h>
 #include <linux/sched/signal.h>
+#include <linux/tty.h>
 #include <linux/uaccess.h>
 #include <uapi/linux/misc/bcm_vk.h>
 
@@ -84,6 +86,9 @@
 #define CODEPUSH_BOOT2_ENTRY		0x60000000
 
 #define BAR_CARD_STATUS			0x410
+/* CARD_STATUS definitions */
+#define CARD_STATUS_TTYVK0_READY	BIT(0)
+#define CARD_STATUS_TTYVK1_READY	BIT(1)
 
 #define BAR_BOOT1_STDALONE_PROGRESS	0x420
 #define BOOT1_STDALONE_SUCCESS		(BIT(13) | BIT(14))
@@ -255,6 +260,19 @@ enum pci_barno {
 
 #define BCM_VK_NUM_TTY 2
 
+struct bcm_vk_tty {
+	struct tty_port port;
+	u32 to_offset;	/* bar offset to use */
+	u32 to_size;	/* to VK buffer size */
+	u32 wr;		/* write offset shadow */
+	u32 from_offset;	/* bar offset to use */
+	u32 from_size;	/* from VK buffer size */
+	u32 rd;		/* read offset shadow */
+	pid_t pid;
+	bool irq_enabled;
+	bool is_opened;		/* tracks tty open/close */
+};
+
 /* VK device max power state, supports 3, full, reduced and low */
 #define MAX_OPP 3
 #define MAX_CARD_INFO_TAG_SIZE 64
@@ -348,6 +366,12 @@ struct bcm_vk {
 	struct miscdevice miscdev;
 	int devid; /* dev id allocated */
 
+	struct tty_driver *tty_drv;
+	struct timer_list serial_timer;
+	struct bcm_vk_tty tty[BCM_VK_NUM_TTY];
+	struct workqueue_struct *tty_wq_thread;
+	struct work_struct tty_wq_work;
+
 	/* Reference-counting to handle file operations */
 	struct kref kref;
 
@@ -466,6 +490,7 @@ int bcm_vk_release(struct inode *inode, struct file *p_file);
 void bcm_vk_release_data(struct kref *kref);
 irqreturn_t bcm_vk_msgq_irqhandler(int irq, void *dev_id);
 irqreturn_t bcm_vk_notf_irqhandler(int irq, void *dev_id);
+irqreturn_t bcm_vk_tty_irqhandler(int irq, void *dev_id);
 int bcm_vk_msg_init(struct bcm_vk *vk);
 void bcm_vk_msg_remove(struct bcm_vk *vk);
 void bcm_vk_drain_msg_on_reset(struct bcm_vk *vk);
@@ -476,6 +501,9 @@ int bcm_vk_send_shutdown_msg(struct bcm_vk *vk, u32 shut_type,
 			     const pid_t pid, const u32 q_num);
 void bcm_to_v_q_doorbell(struct bcm_vk *vk, u32 q_num, u32 db_val);
 int bcm_vk_auto_load_all_images(struct bcm_vk *vk);
+int bcm_vk_tty_init(struct bcm_vk *vk, char *name);
+void bcm_vk_tty_exit(struct bcm_vk *vk);
+void bcm_vk_tty_terminate_tty_user(struct bcm_vk *vk);
 void bcm_vk_hb_init(struct bcm_vk *vk);
 void bcm_vk_hb_deinit(struct bcm_vk *vk);
 void bcm_vk_handle_notf(struct bcm_vk *vk);

drivers/misc/bcm-vk/bcm_vk_dev.c

@@ -525,6 +525,7 @@ void bcm_vk_blk_drv_access(struct bcm_vk *vk)
 			}
 		}
 	}
+	bcm_vk_tty_terminate_tty_user(vk);
 	spin_unlock(&vk->ctx_lock);
 }
 
@@ -1384,6 +1385,20 @@ static int bcm_vk_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 	vk->num_irqs++;
 
+	for (i = 0;
+	     (i < VK_MSIX_TTY_MAX) && (vk->num_irqs < irq);
+	     i++, vk->num_irqs++) {
+		err = devm_request_irq(dev, pci_irq_vector(pdev, vk->num_irqs),
+				       bcm_vk_tty_irqhandler,
+				       IRQF_SHARED, DRV_MODULE_NAME, vk);
+		if (err) {
+			dev_err(dev, "failed request tty IRQ %d for MSIX %d\n",
+				pdev->irq + vk->num_irqs, vk->num_irqs + 1);
+			goto err_irq;
+		}
+		vk->tty[i].irq_enabled = true;
+	}
+
 	id = ida_simple_get(&bcm_vk_ida, 0, 0, GFP_KERNEL);
 	if (id < 0) {
 		err = id;
@@ -1436,6 +1451,11 @@ static int bcm_vk_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto err_destroy_workqueue;
 	}
 
+	snprintf(name, sizeof(name), KBUILD_MODNAME ".%d_ttyVK", id);
+	err = bcm_vk_tty_init(vk, name);
+	if (err)
+		goto err_unregister_panic_notifier;
+
 	/*
 	 * lets trigger an auto download.  We don't want to do it serially here
 	 * because at probing time, it is not supposed to block for a long time.
@@ -1444,7 +1464,7 @@ static int bcm_vk_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (auto_load) {
 		if ((boot_status & BOOT_STATE_MASK) == BROM_RUNNING) {
 			if (bcm_vk_trigger_autoload(vk))
-				goto err_unregister_panic_notifier;
+				goto err_bcm_vk_tty_exit;
 		} else {
 			dev_err(dev,
 				"Auto-load skipped - BROM not in proper state (0x%x)\n",
@@ -1459,6 +1479,9 @@ static int bcm_vk_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	return 0;
 
+err_bcm_vk_tty_exit:
+	bcm_vk_tty_exit(vk);
+
 err_unregister_panic_notifier:
 	atomic_notifier_chain_unregister(&panic_notifier_list,
 					 &vk->panic_nb);
@@ -1536,6 +1559,9 @@ static void bcm_vk_remove(struct pci_dev *pdev)
 	atomic_notifier_chain_unregister(&panic_notifier_list,
 					 &vk->panic_nb);
 
+	bcm_vk_msg_remove(vk);
+	bcm_vk_tty_exit(vk);
+
 	if (vk->tdma_vaddr)
 		dma_free_coherent(&pdev->dev, nr_scratch_pages * PAGE_SIZE,
 				  vk->tdma_vaddr, vk->tdma_addr);
@@ -1554,6 +1580,8 @@ static void bcm_vk_remove(struct pci_dev *pdev)
 
 	cancel_work_sync(&vk->wq_work);
 	destroy_workqueue(vk->wq_thread);
+	cancel_work_sync(&vk->tty_wq_work);
+	destroy_workqueue(vk->tty_wq_thread);
 
 	for (i = 0; i < MAX_BAR; i++) {
 		if (vk->bar[i])