1 /*
2  * Copyright (C) 2017 Broadcom
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation version 2.
7  *
8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9  * kind, whether express or implied; without even the implied warranty
10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  */
13 
14 /*
15  * This driver provides reset support for Broadcom FlexRM ring manager
16  * to VFIO platform.
17  */
18 
19 #include <linux/delay.h>
20 #include <linux/device.h>
21 #include <linux/init.h>
22 #include <linux/io.h>
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 
26 #include "vfio_platform_private.h"
27 
28 /* FlexRM configuration */
29 #define RING_REGS_SIZE					0x10000
30 #define RING_VER_MAGIC					0x76303031
31 
32 /* Per-Ring register offsets */
33 #define RING_VER					0x000
34 #define RING_CONTROL					0x034
35 #define RING_FLUSH_DONE					0x038
36 
37 /* Register RING_CONTROL fields */
38 #define CONTROL_FLUSH_SHIFT				5
39 
40 /* Register RING_FLUSH_DONE fields */
41 #define FLUSH_DONE_MASK					0x1
42 
43 static int vfio_platform_bcmflexrm_shutdown(void __iomem *ring)
44 {
45 	unsigned int timeout;
46 
47 	/* Disable/inactivate ring */
48 	writel_relaxed(0x0, ring + RING_CONTROL);
49 
50 	/* Set ring flush state */
51 	timeout = 1000; /* timeout of 1s */
52 	writel_relaxed(BIT(CONTROL_FLUSH_SHIFT), ring + RING_CONTROL);
53 	do {
54 		if (readl_relaxed(ring + RING_FLUSH_DONE) &
55 		    FLUSH_DONE_MASK)
56 			break;
57 		mdelay(1);
58 	} while (--timeout);
59 	if (!timeout)
60 		return -ETIMEDOUT;
61 
62 	/* Clear ring flush state */
63 	timeout = 1000; /* timeout of 1s */
64 	writel_relaxed(0x0, ring + RING_CONTROL);
65 	do {
66 		if (!(readl_relaxed(ring + RING_FLUSH_DONE) &
67 		      FLUSH_DONE_MASK))
68 			break;
69 		mdelay(1);
70 	} while (--timeout);
71 	if (!timeout)
72 		return -ETIMEDOUT;
73 
74 	return 0;
75 }
76 
77 static int vfio_platform_bcmflexrm_reset(struct vfio_platform_device *vdev)
78 {
79 	void __iomem *ring;
80 	int rc = 0, ret = 0, ring_num = 0;
81 	struct vfio_platform_region *reg = &vdev->regions[0];
82 
83 	/* Map FlexRM ring registers if not mapped */
84 	if (!reg->ioaddr) {
85 		reg->ioaddr = ioremap_nocache(reg->addr, reg->size);
86 		if (!reg->ioaddr)
87 			return -ENOMEM;
88 	}
89 
90 	/* Discover and shutdown each FlexRM ring */
91 	for (ring = reg->ioaddr;
92 	     ring < (reg->ioaddr + reg->size); ring += RING_REGS_SIZE) {
93 		if (readl_relaxed(ring + RING_VER) == RING_VER_MAGIC) {
94 			rc = vfio_platform_bcmflexrm_shutdown(ring);
95 			if (rc) {
96 				dev_warn(vdev->device,
97 					 "FlexRM ring%d shutdown error %d\n",
98 					 ring_num, rc);
99 				ret |= rc;
100 			}
101 			ring_num++;
102 		}
103 	}
104 
105 	return ret;
106 }
107 
108 module_vfio_reset_handler("brcm,iproc-flexrm-mbox",
109 			  vfio_platform_bcmflexrm_reset);
110 
111 MODULE_LICENSE("GPL v2");
112 MODULE_AUTHOR("Anup Patel <anup.patel@broadcom.com>");
113 MODULE_DESCRIPTION("Reset support for Broadcom FlexRM VFIO platform device");
114