1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright 2019 Google Inc
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * Provides a simple driver to control the ASPEED P2A interface which allows
11 * the host to read and write to various regions of the BMC's memory.
12 */
13
14#include <linux/fs.h>
15#include <linux/io.h>
16#include <linux/mfd/syscon.h>
17#include <linux/miscdevice.h>
18#include <linux/mm.h>
19#include <linux/module.h>
20#include <linux/mutex.h>
21#include <linux/of.h>
22#include <linux/of_address.h>
23#include <linux/platform_device.h>
24#include <linux/regmap.h>
25#include <linux/slab.h>
26#include <linux/uaccess.h>
27
28#include <linux/aspeed-p2a-ctrl.h>
29
30#define DEVICE_NAME "aspeed-p2a-ctrl"
31
32/* SCU2C is a Misc. Control Register. */
33#define SCU2C 0x2c
34/* SCU180 is the PCIe Configuration Setting Control Register. */
35#define SCU180 0x180
36/* Bit 1 controls the P2A bridge, while bit 0 controls the entire VGA device
37 * on the PCI bus.
38 */
39#define SCU180_ENP2A BIT(1)
40
41/* The ast2400/2500 both have six ranges. */
42#define P2A_REGION_COUNT 6
43
44struct region {
45 u64 min;
46 u64 max;
47 u32 bit;
48};
49
50struct aspeed_p2a_model_data {
51 /* min, max, bit */
52 struct region regions[P2A_REGION_COUNT];
53};
54
55struct aspeed_p2a_ctrl {
56 struct miscdevice miscdev;
57 struct regmap *regmap;
58
59 const struct aspeed_p2a_model_data *config;
60
61 /* Access to these needs to be locked, held via probe, mapping ioctl,
62 * and release, remove.
63 */
64 struct mutex tracking;
65 u32 readers;
66 u32 readerwriters[P2A_REGION_COUNT];
67
68 phys_addr_t mem_base;
69 resource_size_t mem_size;
70};
71
72struct aspeed_p2a_user {
73 struct file *file;
74 struct aspeed_p2a_ctrl *parent;
75
76 /* The entire memory space is opened for reading once the bridge is
77 * enabled, therefore this needs only to be tracked once per user.
78 * If any user has it open for read, the bridge must stay enabled.
79 */
80 u32 read;
81
82 /* Each entry of the array corresponds to a P2A Region. If the user
83 * opens for read or readwrite, the reference goes up here. On
84 * release, this array is walked and references adjusted accordingly.
85 */
86 u32 readwrite[P2A_REGION_COUNT];
87};
88
89static void aspeed_p2a_enable_bridge(struct aspeed_p2a_ctrl *p2a_ctrl)
90{
91 regmap_update_bits(map: p2a_ctrl->regmap,
92 SCU180, SCU180_ENP2A, SCU180_ENP2A);
93}
94
95static void aspeed_p2a_disable_bridge(struct aspeed_p2a_ctrl *p2a_ctrl)
96{
97 regmap_update_bits(map: p2a_ctrl->regmap, SCU180, SCU180_ENP2A, val: 0);
98}
99
100static int aspeed_p2a_mmap(struct file *file, struct vm_area_struct *vma)
101{
102 unsigned long vsize;
103 pgprot_t prot;
104 struct aspeed_p2a_user *priv = file->private_data;
105 struct aspeed_p2a_ctrl *ctrl = priv->parent;
106
107 if (ctrl->mem_base == 0 && ctrl->mem_size == 0)
108 return -EINVAL;
109
110 vsize = vma->vm_end - vma->vm_start;
111 prot = vma->vm_page_prot;
112
113 if (vma->vm_pgoff + vma_pages(vma) > ctrl->mem_size >> PAGE_SHIFT)
114 return -EINVAL;
115
116 /* ast2400/2500 AHB accesses are not cache coherent */
117 prot = pgprot_noncached(prot);
118
119 if (remap_pfn_range(vma, addr: vma->vm_start,
120 pfn: (ctrl->mem_base >> PAGE_SHIFT) + vma->vm_pgoff,
121 size: vsize, prot))
122 return -EAGAIN;
123
124 return 0;
125}
126
127static bool aspeed_p2a_region_acquire(struct aspeed_p2a_user *priv,
128 struct aspeed_p2a_ctrl *ctrl,
129 struct aspeed_p2a_ctrl_mapping *map)
130{
131 int i;
132 u64 base, end;
133 bool matched = false;
134
135 base = map->addr;
136 end = map->addr + (map->length - 1);
137
138 /* If the value is a legal u32, it will find a match. */
139 for (i = 0; i < P2A_REGION_COUNT; i++) {
140 const struct region *curr = &ctrl->config->regions[i];
141
142 /* If the top of this region is lower than your base, skip it.
143 */
144 if (curr->max < base)
145 continue;
146
147 /* If the bottom of this region is higher than your end, bail.
148 */
149 if (curr->min > end)
150 break;
151
152 /* Lock this and update it, therefore it someone else is
153 * closing their file out, this'll preserve the increment.
154 */
155 mutex_lock(&ctrl->tracking);
156 ctrl->readerwriters[i] += 1;
157 mutex_unlock(lock: &ctrl->tracking);
158
159 /* Track with the user, so when they close their file, we can
160 * decrement properly.
161 */
162 priv->readwrite[i] += 1;
163
164 /* Enable the region as read-write. */
165 regmap_update_bits(map: ctrl->regmap, SCU2C, mask: curr->bit, val: 0);
166 matched = true;
167 }
168
169 return matched;
170}
171
172static long aspeed_p2a_ioctl(struct file *file, unsigned int cmd,
173 unsigned long data)
174{
175 struct aspeed_p2a_user *priv = file->private_data;
176 struct aspeed_p2a_ctrl *ctrl = priv->parent;
177 void __user *arg = (void __user *)data;
178 struct aspeed_p2a_ctrl_mapping map;
179
180 if (copy_from_user(to: &map, from: arg, n: sizeof(map)))
181 return -EFAULT;
182
183 switch (cmd) {
184 case ASPEED_P2A_CTRL_IOCTL_SET_WINDOW:
185 /* If they want a region to be read-only, since the entire
186 * region is read-only once enabled, we just need to track this
187 * user wants to read from the bridge, and if it's not enabled.
188 * Enable it.
189 */
190 if (map.flags == ASPEED_P2A_CTRL_READ_ONLY) {
191 mutex_lock(&ctrl->tracking);
192 ctrl->readers += 1;
193 mutex_unlock(lock: &ctrl->tracking);
194
195 /* Track with the user, so when they close their file,
196 * we can decrement properly.
197 */
198 priv->read += 1;
199 } else if (map.flags == ASPEED_P2A_CTRL_READWRITE) {
200 /* If we don't acquire any region return error. */
201 if (!aspeed_p2a_region_acquire(priv, ctrl, map: &map)) {
202 return -EINVAL;
203 }
204 } else {
205 /* Invalid map flags. */
206 return -EINVAL;
207 }
208
209 aspeed_p2a_enable_bridge(p2a_ctrl: ctrl);
210 return 0;
211 case ASPEED_P2A_CTRL_IOCTL_GET_MEMORY_CONFIG:
212 /* This is a request for the memory-region and corresponding
213 * length that is used by the driver for mmap.
214 */
215
216 map.flags = 0;
217 map.addr = ctrl->mem_base;
218 map.length = ctrl->mem_size;
219
220 return copy_to_user(to: arg, from: &map, n: sizeof(map)) ? -EFAULT : 0;
221 }
222
223 return -EINVAL;
224}
225
226
227/*
228 * When a user opens this file, we create a structure to track their mappings.
229 *
230 * A user can map a region as read-only (bridge enabled), or read-write (bit
231 * flipped, and bridge enabled). Either way, this tracking is used, s.t. when
232 * they release the device references are handled.
233 *
234 * The bridge is not enabled until a user calls an ioctl to map a region,
235 * simply opening the device does not enable it.
236 */
237static int aspeed_p2a_open(struct inode *inode, struct file *file)
238{
239 struct aspeed_p2a_user *priv;
240
241 priv = kmalloc(size: sizeof(*priv), GFP_KERNEL);
242 if (!priv)
243 return -ENOMEM;
244
245 priv->file = file;
246 priv->read = 0;
247 memset(priv->readwrite, 0, sizeof(priv->readwrite));
248
249 /* The file's private_data is initialized to the p2a_ctrl. */
250 priv->parent = file->private_data;
251
252 /* Set the file's private_data to the user's data. */
253 file->private_data = priv;
254
255 return 0;
256}
257
258/*
259 * This will close the users mappings. It will go through what they had opened
260 * for readwrite, and decrement those counts. If at the end, this is the last
261 * user, it'll close the bridge.
262 */
263static int aspeed_p2a_release(struct inode *inode, struct file *file)
264{
265 int i;
266 u32 bits = 0;
267 bool open_regions = false;
268 struct aspeed_p2a_user *priv = file->private_data;
269
270 /* Lock others from changing these values until everything is updated
271 * in one pass.
272 */
273 mutex_lock(&priv->parent->tracking);
274
275 priv->parent->readers -= priv->read;
276
277 for (i = 0; i < P2A_REGION_COUNT; i++) {
278 priv->parent->readerwriters[i] -= priv->readwrite[i];
279
280 if (priv->parent->readerwriters[i] > 0)
281 open_regions = true;
282 else
283 bits |= priv->parent->config->regions[i].bit;
284 }
285
286 /* Setting a bit to 1 disables the region, so let's just OR with the
287 * above to disable any.
288 */
289
290 /* Note, if another user is trying to ioctl, they can't grab tracking,
291 * and therefore can't grab either register mutex.
292 * If another user is trying to close, they can't grab tracking either.
293 */
294 regmap_update_bits(map: priv->parent->regmap, SCU2C, mask: bits, val: bits);
295
296 /* If parent->readers is zero and open windows is 0, disable the
297 * bridge.
298 */
299 if (!open_regions && priv->parent->readers == 0)
300 aspeed_p2a_disable_bridge(p2a_ctrl: priv->parent);
301
302 mutex_unlock(lock: &priv->parent->tracking);
303
304 kfree(objp: priv);
305
306 return 0;
307}
308
309static const struct file_operations aspeed_p2a_ctrl_fops = {
310 .owner = THIS_MODULE,
311 .mmap = aspeed_p2a_mmap,
312 .unlocked_ioctl = aspeed_p2a_ioctl,
313 .open = aspeed_p2a_open,
314 .release = aspeed_p2a_release,
315};
316
317/* The regions are controlled by SCU2C */
318static void aspeed_p2a_disable_all(struct aspeed_p2a_ctrl *p2a_ctrl)
319{
320 int i;
321 u32 value = 0;
322
323 for (i = 0; i < P2A_REGION_COUNT; i++)
324 value |= p2a_ctrl->config->regions[i].bit;
325
326 regmap_update_bits(map: p2a_ctrl->regmap, SCU2C, mask: value, val: value);
327
328 /* Disable the bridge. */
329 aspeed_p2a_disable_bridge(p2a_ctrl);
330}
331
332static int aspeed_p2a_ctrl_probe(struct platform_device *pdev)
333{
334 struct aspeed_p2a_ctrl *misc_ctrl;
335 struct device *dev;
336 struct resource resm;
337 struct device_node *node;
338 int rc = 0;
339
340 dev = &pdev->dev;
341
342 misc_ctrl = devm_kzalloc(dev, size: sizeof(*misc_ctrl), GFP_KERNEL);
343 if (!misc_ctrl)
344 return -ENOMEM;
345
346 mutex_init(&misc_ctrl->tracking);
347
348 /* optional. */
349 node = of_parse_phandle(np: dev->of_node, phandle_name: "memory-region", index: 0);
350 if (node) {
351 rc = of_address_to_resource(dev: node, index: 0, r: &resm);
352 of_node_put(node);
353 if (rc) {
354 dev_err(dev, "Couldn't address to resource for reserved memory\n");
355 return -ENODEV;
356 }
357
358 misc_ctrl->mem_size = resource_size(res: &resm);
359 misc_ctrl->mem_base = resm.start;
360 }
361
362 misc_ctrl->regmap = syscon_node_to_regmap(np: pdev->dev.parent->of_node);
363 if (IS_ERR(ptr: misc_ctrl->regmap)) {
364 dev_err(dev, "Couldn't get regmap\n");
365 return -ENODEV;
366 }
367
368 misc_ctrl->config = of_device_get_match_data(dev);
369
370 dev_set_drvdata(dev: &pdev->dev, data: misc_ctrl);
371
372 aspeed_p2a_disable_all(p2a_ctrl: misc_ctrl);
373
374 misc_ctrl->miscdev.minor = MISC_DYNAMIC_MINOR;
375 misc_ctrl->miscdev.name = DEVICE_NAME;
376 misc_ctrl->miscdev.fops = &aspeed_p2a_ctrl_fops;
377 misc_ctrl->miscdev.parent = dev;
378
379 rc = misc_register(misc: &misc_ctrl->miscdev);
380 if (rc)
381 dev_err(dev, "Unable to register device\n");
382
383 return rc;
384}
385
386static void aspeed_p2a_ctrl_remove(struct platform_device *pdev)
387{
388 struct aspeed_p2a_ctrl *p2a_ctrl = dev_get_drvdata(dev: &pdev->dev);
389
390 misc_deregister(misc: &p2a_ctrl->miscdev);
391}
392
393#define SCU2C_DRAM BIT(25)
394#define SCU2C_SPI BIT(24)
395#define SCU2C_SOC BIT(23)
396#define SCU2C_FLASH BIT(22)
397
398static const struct aspeed_p2a_model_data ast2400_model_data = {
399 .regions = {
400 {0x00000000, 0x17FFFFFF, SCU2C_FLASH},
401 {0x18000000, 0x1FFFFFFF, SCU2C_SOC},
402 {0x20000000, 0x2FFFFFFF, SCU2C_FLASH},
403 {0x30000000, 0x3FFFFFFF, SCU2C_SPI},
404 {0x40000000, 0x5FFFFFFF, SCU2C_DRAM},
405 {0x60000000, 0xFFFFFFFF, SCU2C_SOC},
406 }
407};
408
409static const struct aspeed_p2a_model_data ast2500_model_data = {
410 .regions = {
411 {0x00000000, 0x0FFFFFFF, SCU2C_FLASH},
412 {0x10000000, 0x1FFFFFFF, SCU2C_SOC},
413 {0x20000000, 0x3FFFFFFF, SCU2C_FLASH},
414 {0x40000000, 0x5FFFFFFF, SCU2C_SOC},
415 {0x60000000, 0x7FFFFFFF, SCU2C_SPI},
416 {0x80000000, 0xFFFFFFFF, SCU2C_DRAM},
417 }
418};
419
420static const struct of_device_id aspeed_p2a_ctrl_match[] = {
421 { .compatible = "aspeed,ast2400-p2a-ctrl",
422 .data = &ast2400_model_data },
423 { .compatible = "aspeed,ast2500-p2a-ctrl",
424 .data = &ast2500_model_data },
425 { },
426};
427
428static struct platform_driver aspeed_p2a_ctrl_driver = {
429 .driver = {
430 .name = DEVICE_NAME,
431 .of_match_table = aspeed_p2a_ctrl_match,
432 },
433 .probe = aspeed_p2a_ctrl_probe,
434 .remove_new = aspeed_p2a_ctrl_remove,
435};
436
437module_platform_driver(aspeed_p2a_ctrl_driver);
438
439MODULE_DEVICE_TABLE(of, aspeed_p2a_ctrl_match);
440MODULE_LICENSE("GPL");
441MODULE_AUTHOR("Patrick Venture <venture@google.com>");
442MODULE_DESCRIPTION("Control for aspeed 2400/2500 P2A VGA HOST to BMC mappings");
443

source code of linux/drivers/soc/aspeed/aspeed-p2a-ctrl.c