1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright(c) 2016-2018 Intel Corporation. All rights reserved.
4 */
5#include <linux/dma-mapping.h>
6#include <linux/mei.h>
7
8#include "mei_dev.h"
9
10/**
11 * mei_dmam_dscr_alloc() - allocate a managed coherent buffer
12 *     for the dma descriptor
13 * @dev: mei_device
14 * @dscr: dma descriptor
15 *
16 * Return:
17 * * 0       - on success or zero allocation request
18 * * -EINVAL - if size is not power of 2
19 * * -ENOMEM - of allocation has failed
20 */
21static int mei_dmam_dscr_alloc(struct mei_device *dev,
22			       struct mei_dma_dscr *dscr)
23{
24	if (!dscr->size)
25		return 0;
26
27	if (WARN_ON(!is_power_of_2(dscr->size)))
28		return -EINVAL;
29
30	if (dscr->vaddr)
31		return 0;
32
33	dscr->vaddr = dmam_alloc_coherent(dev->dev, dscr->size, &dscr->daddr,
34					  GFP_KERNEL);
35	if (!dscr->vaddr)
36		return -ENOMEM;
37
38	return 0;
39}
40
41/**
42 * mei_dmam_dscr_free() - free a managed coherent buffer
43 *     from the dma descriptor
44 * @dev: mei_device
45 * @dscr: dma descriptor
46 */
47static void mei_dmam_dscr_free(struct mei_device *dev,
48			       struct mei_dma_dscr *dscr)
49{
50	if (!dscr->vaddr)
51		return;
52
53	dmam_free_coherent(dev->dev, dscr->size, dscr->vaddr, dscr->daddr);
54	dscr->vaddr = NULL;
55}
56
57/**
58 * mei_dmam_ring_free() - free dma ring buffers
59 * @dev: mei device
60 */
61void mei_dmam_ring_free(struct mei_device *dev)
62{
63	int i;
64
65	for (i = 0; i < DMA_DSCR_NUM; i++)
66		mei_dmam_dscr_free(dev, &dev->dr_dscr[i]);
67}
68
69/**
70 * mei_dmam_ring_alloc() - allocate dma ring buffers
71 * @dev: mei device
72 *
73 * Return: -ENOMEM on allocation failure 0 otherwise
74 */
75int mei_dmam_ring_alloc(struct mei_device *dev)
76{
77	int i;
78
79	for (i = 0; i < DMA_DSCR_NUM; i++)
80		if (mei_dmam_dscr_alloc(dev, &dev->dr_dscr[i]))
81			goto err;
82
83	return 0;
84
85err:
86	mei_dmam_ring_free(dev);
87	return -ENOMEM;
88}
89
90/**
91 * mei_dma_ring_is_allocated() - check if dma ring is allocated
92 * @dev: mei device
93 *
94 * Return: true if dma ring is allocated
95 */
96bool mei_dma_ring_is_allocated(struct mei_device *dev)
97{
98	return !!dev->dr_dscr[DMA_DSCR_HOST].vaddr;
99}
100
101static inline
102struct hbm_dma_ring_ctrl *mei_dma_ring_ctrl(struct mei_device *dev)
103{
104	return (struct hbm_dma_ring_ctrl *)dev->dr_dscr[DMA_DSCR_CTRL].vaddr;
105}
106
107/**
108 * mei_dma_ring_reset() - reset the dma control block
109 * @dev: mei device
110 */
111void mei_dma_ring_reset(struct mei_device *dev)
112{
113	struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev);
114
115	if (!ctrl)
116		return;
117
118	memset(ctrl, 0, sizeof(*ctrl));
119}
120
121/**
122 * mei_dma_copy_from() - copy from dma ring into buffer
123 * @dev: mei device
124 * @buf: data buffer
125 * @offset: offset in slots.
126 * @n: number of slots to copy.
127 */
128static size_t mei_dma_copy_from(struct mei_device *dev, unsigned char *buf,
129				u32 offset, u32 n)
130{
131	unsigned char *dbuf = dev->dr_dscr[DMA_DSCR_DEVICE].vaddr;
132
133	size_t b_offset = offset << 2;
134	size_t b_n = n << 2;
135
136	memcpy(buf, dbuf + b_offset, b_n);
137
138	return b_n;
139}
140
141/**
142 * mei_dma_copy_to() - copy to a buffer to the dma ring
143 * @dev: mei device
144 * @buf: data buffer
145 * @offset: offset in slots.
146 * @n: number of slots to copy.
147 */
148static size_t mei_dma_copy_to(struct mei_device *dev, unsigned char *buf,
149			      u32 offset, u32 n)
150{
151	unsigned char *hbuf = dev->dr_dscr[DMA_DSCR_HOST].vaddr;
152
153	size_t b_offset = offset << 2;
154	size_t b_n = n << 2;
155
156	memcpy(hbuf + b_offset, buf, b_n);
157
158	return b_n;
159}
160
161/**
162 * mei_dma_ring_read() - read data from the ring
163 * @dev: mei device
164 * @buf: buffer to read into: may be NULL in case of droping the data.
165 * @len: length to read.
166 */
167void mei_dma_ring_read(struct mei_device *dev, unsigned char *buf, u32 len)
168{
169	struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev);
170	u32 dbuf_depth;
171	u32 rd_idx, rem, slots;
172
173	if (WARN_ON(!ctrl))
174		return;
175
176	dev_dbg(dev->dev, "reading from dma %u bytes\n", len);
177
178	if (!len)
179		return;
180
181	dbuf_depth = dev->dr_dscr[DMA_DSCR_DEVICE].size >> 2;
182	rd_idx = READ_ONCE(ctrl->dbuf_rd_idx) & (dbuf_depth - 1);
183	slots = mei_data2slots(len);
184
185	/* if buf is NULL we drop the packet by advancing the pointer.*/
186	if (!buf)
187		goto out;
188
189	if (rd_idx + slots > dbuf_depth) {
190		buf += mei_dma_copy_from(dev, buf, rd_idx, dbuf_depth - rd_idx);
191		rem = slots - (dbuf_depth - rd_idx);
192		rd_idx = 0;
193	} else {
194		rem = slots;
195	}
196
197	mei_dma_copy_from(dev, buf, rd_idx, rem);
198out:
199	WRITE_ONCE(ctrl->dbuf_rd_idx, ctrl->dbuf_rd_idx + slots);
200}
201
202static inline u32 mei_dma_ring_hbuf_depth(struct mei_device *dev)
203{
204	return dev->dr_dscr[DMA_DSCR_HOST].size >> 2;
205}
206
207/**
208 * mei_dma_ring_empty_slots() - calaculate number of empty slots in dma ring
209 * @dev: mei_device
210 *
211 * Return: number of empty slots
212 */
213u32 mei_dma_ring_empty_slots(struct mei_device *dev)
214{
215	struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev);
216	u32 wr_idx, rd_idx, hbuf_depth, empty;
217
218	if (!mei_dma_ring_is_allocated(dev))
219		return 0;
220
221	if (WARN_ON(!ctrl))
222		return 0;
223
224	/* easier to work in slots */
225	hbuf_depth = mei_dma_ring_hbuf_depth(dev);
226	rd_idx = READ_ONCE(ctrl->hbuf_rd_idx);
227	wr_idx = READ_ONCE(ctrl->hbuf_wr_idx);
228
229	if (rd_idx > wr_idx)
230		empty = rd_idx - wr_idx;
231	else
232		empty = hbuf_depth - (wr_idx - rd_idx);
233
234	return empty;
235}
236
237/**
238 * mei_dma_ring_write - write data to dma ring host buffer
239 *
240 * @dev: mei_device
241 * @buf: data will be written
242 * @len: data length
243 */
244void mei_dma_ring_write(struct mei_device *dev, unsigned char *buf, u32 len)
245{
246	struct hbm_dma_ring_ctrl *ctrl = mei_dma_ring_ctrl(dev);
247	u32 hbuf_depth;
248	u32 wr_idx, rem, slots;
249
250	if (WARN_ON(!ctrl))
251		return;
252
253	dev_dbg(dev->dev, "writing to dma %u bytes\n", len);
254	hbuf_depth = mei_dma_ring_hbuf_depth(dev);
255	wr_idx = READ_ONCE(ctrl->hbuf_wr_idx) & (hbuf_depth - 1);
256	slots = mei_data2slots(len);
257
258	if (wr_idx + slots > hbuf_depth) {
259		buf += mei_dma_copy_to(dev, buf, wr_idx, hbuf_depth - wr_idx);
260		rem = slots - (hbuf_depth - wr_idx);
261		wr_idx = 0;
262	} else {
263		rem = slots;
264	}
265
266	mei_dma_copy_to(dev, buf, wr_idx, rem);
267
268	WRITE_ONCE(ctrl->hbuf_wr_idx, ctrl->hbuf_wr_idx + slots);
269}
270