1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) ST-Ericsson AB 2010
4 * Author: Daniel Martensson
5 */
6 #include <linux/module.h>
7 #include <linux/device.h>
8 #include <linux/platform_device.h>
9 #include <linux/string.h>
10 #include <linux/semaphore.h>
11 #include <linux/workqueue.h>
12 #include <linux/completion.h>
13 #include <linux/list.h>
14 #include <linux/interrupt.h>
15 #include <linux/dma-mapping.h>
16 #include <linux/delay.h>
17 #include <linux/sched.h>
18 #include <linux/debugfs.h>
19 #include <net/caif/caif_spi.h>
20
21 #ifndef CONFIG_CAIF_SPI_SYNC
22 #define SPI_DATA_POS 0
forward_to_spi_cmd(struct cfspi * cfspi)23 static inline int forward_to_spi_cmd(struct cfspi *cfspi)
24 {
25 return cfspi->rx_cpck_len;
26 }
27 #else
28 #define SPI_DATA_POS SPI_CMD_SZ
forward_to_spi_cmd(struct cfspi * cfspi)29 static inline int forward_to_spi_cmd(struct cfspi *cfspi)
30 {
31 return 0;
32 }
33 #endif
34
35 int spi_frm_align = 2;
36
37 /*
38 * SPI padding options.
39 * Warning: must be a base of 2 (& operation used) and can not be zero !
40 */
41 int spi_up_head_align = 1 << 1;
42 int spi_up_tail_align = 1 << 0;
43 int spi_down_head_align = 1 << 2;
44 int spi_down_tail_align = 1 << 1;
45
46 #ifdef CONFIG_DEBUG_FS
debugfs_store_prev(struct cfspi * cfspi)47 static inline void debugfs_store_prev(struct cfspi *cfspi)
48 {
49 /* Store previous command for debugging reasons.*/
50 cfspi->pcmd = cfspi->cmd;
51 /* Store previous transfer. */
52 cfspi->tx_ppck_len = cfspi->tx_cpck_len;
53 cfspi->rx_ppck_len = cfspi->rx_cpck_len;
54 }
55 #else
debugfs_store_prev(struct cfspi * cfspi)56 static inline void debugfs_store_prev(struct cfspi *cfspi)
57 {
58 }
59 #endif
60
cfspi_xfer(struct work_struct * work)61 void cfspi_xfer(struct work_struct *work)
62 {
63 struct cfspi *cfspi;
64 u8 *ptr = NULL;
65 unsigned long flags;
66 int ret;
67 cfspi = container_of(work, struct cfspi, work);
68
69 /* Initialize state. */
70 cfspi->cmd = SPI_CMD_EOT;
71
72 for (;;) {
73
74 cfspi_dbg_state(cfspi, CFSPI_STATE_WAITING);
75
76 /* Wait for master talk or transmit event. */
77 wait_event_interruptible(cfspi->wait,
78 test_bit(SPI_XFER, &cfspi->state) ||
79 test_bit(SPI_TERMINATE, &cfspi->state));
80
81 if (test_bit(SPI_TERMINATE, &cfspi->state))
82 return;
83
84 #if CFSPI_DBG_PREFILL
85 /* Prefill buffers for easier debugging. */
86 memset(cfspi->xfer.va_tx, 0xFF, SPI_DMA_BUF_LEN);
87 memset(cfspi->xfer.va_rx, 0xFF, SPI_DMA_BUF_LEN);
88 #endif /* CFSPI_DBG_PREFILL */
89
90 cfspi_dbg_state(cfspi, CFSPI_STATE_AWAKE);
91
92 /* Check whether we have a committed frame. */
93 if (cfspi->tx_cpck_len) {
94 int len;
95
96 cfspi_dbg_state(cfspi, CFSPI_STATE_FETCH_PKT);
97
98 /* Copy committed SPI frames after the SPI indication. */
99 ptr = (u8 *) cfspi->xfer.va_tx;
100 ptr += SPI_IND_SZ;
101 len = cfspi_xmitfrm(cfspi, ptr, cfspi->tx_cpck_len);
102 WARN_ON(len != cfspi->tx_cpck_len);
103 }
104
105 cfspi_dbg_state(cfspi, CFSPI_STATE_GET_NEXT);
106
107 /* Get length of next frame to commit. */
108 cfspi->tx_npck_len = cfspi_xmitlen(cfspi);
109
110 WARN_ON(cfspi->tx_npck_len > SPI_DMA_BUF_LEN);
111
112 /*
113 * Add indication and length at the beginning of the frame,
114 * using little endian.
115 */
116 ptr = (u8 *) cfspi->xfer.va_tx;
117 *ptr++ = SPI_CMD_IND;
118 *ptr++ = (SPI_CMD_IND & 0xFF00) >> 8;
119 *ptr++ = cfspi->tx_npck_len & 0x00FF;
120 *ptr++ = (cfspi->tx_npck_len & 0xFF00) >> 8;
121
122 /* Calculate length of DMAs. */
123 cfspi->xfer.tx_dma_len = cfspi->tx_cpck_len + SPI_IND_SZ;
124 cfspi->xfer.rx_dma_len = cfspi->rx_cpck_len + SPI_CMD_SZ;
125
126 /* Add SPI TX frame alignment padding, if necessary. */
127 if (cfspi->tx_cpck_len &&
128 (cfspi->xfer.tx_dma_len % spi_frm_align)) {
129
130 cfspi->xfer.tx_dma_len += spi_frm_align -
131 (cfspi->xfer.tx_dma_len % spi_frm_align);
132 }
133
134 /* Add SPI RX frame alignment padding, if necessary. */
135 if (cfspi->rx_cpck_len &&
136 (cfspi->xfer.rx_dma_len % spi_frm_align)) {
137
138 cfspi->xfer.rx_dma_len += spi_frm_align -
139 (cfspi->xfer.rx_dma_len % spi_frm_align);
140 }
141
142 cfspi_dbg_state(cfspi, CFSPI_STATE_INIT_XFER);
143
144 /* Start transfer. */
145 ret = cfspi->dev->init_xfer(&cfspi->xfer, cfspi->dev);
146 WARN_ON(ret);
147
148 cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_ACTIVE);
149
150 /*
151 * TODO: We might be able to make an assumption if this is the
152 * first loop. Make sure that minimum toggle time is respected.
153 */
154 udelay(MIN_TRANSITION_TIME_USEC);
155
156 cfspi_dbg_state(cfspi, CFSPI_STATE_SIG_ACTIVE);
157
158 /* Signal that we are ready to receive data. */
159 cfspi->dev->sig_xfer(true, cfspi->dev);
160
161 cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_XFER_DONE);
162
163 /* Wait for transfer completion. */
164 wait_for_completion(&cfspi->comp);
165
166 cfspi_dbg_state(cfspi, CFSPI_STATE_XFER_DONE);
167
168 if (cfspi->cmd == SPI_CMD_EOT) {
169 /*
170 * Clear the master talk bit. A xfer is always at
171 * least two bursts.
172 */
173 clear_bit(SPI_SS_ON, &cfspi->state);
174 }
175
176 cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_INACTIVE);
177
178 /* Make sure that the minimum toggle time is respected. */
179 if (SPI_XFER_TIME_USEC(cfspi->xfer.tx_dma_len,
180 cfspi->dev->clk_mhz) <
181 MIN_TRANSITION_TIME_USEC) {
182
183 udelay(MIN_TRANSITION_TIME_USEC -
184 SPI_XFER_TIME_USEC
185 (cfspi->xfer.tx_dma_len, cfspi->dev->clk_mhz));
186 }
187
188 cfspi_dbg_state(cfspi, CFSPI_STATE_SIG_INACTIVE);
189
190 /* De-assert transfer signal. */
191 cfspi->dev->sig_xfer(false, cfspi->dev);
192
193 /* Check whether we received a CAIF packet. */
194 if (cfspi->rx_cpck_len) {
195 int len;
196
197 cfspi_dbg_state(cfspi, CFSPI_STATE_DELIVER_PKT);
198
199 /* Parse SPI frame. */
200 ptr = ((u8 *)(cfspi->xfer.va_rx + SPI_DATA_POS));
201
202 len = cfspi_rxfrm(cfspi, ptr, cfspi->rx_cpck_len);
203 WARN_ON(len != cfspi->rx_cpck_len);
204 }
205
206 /* Check the next SPI command and length. */
207 ptr = (u8 *) cfspi->xfer.va_rx;
208
209 ptr += forward_to_spi_cmd(cfspi);
210
211 cfspi->cmd = *ptr++;
212 cfspi->cmd |= ((*ptr++) << 8) & 0xFF00;
213 cfspi->rx_npck_len = *ptr++;
214 cfspi->rx_npck_len |= ((*ptr++) << 8) & 0xFF00;
215
216 WARN_ON(cfspi->rx_npck_len > SPI_DMA_BUF_LEN);
217 WARN_ON(cfspi->cmd > SPI_CMD_EOT);
218
219 debugfs_store_prev(cfspi);
220
221 /* Check whether the master issued an EOT command. */
222 if (cfspi->cmd == SPI_CMD_EOT) {
223 /* Reset state. */
224 cfspi->tx_cpck_len = 0;
225 cfspi->rx_cpck_len = 0;
226 } else {
227 /* Update state. */
228 cfspi->tx_cpck_len = cfspi->tx_npck_len;
229 cfspi->rx_cpck_len = cfspi->rx_npck_len;
230 }
231
232 /*
233 * Check whether we need to clear the xfer bit.
234 * Spin lock needed for packet insertion.
235 * Test and clear of different bits
236 * are not supported.
237 */
238 spin_lock_irqsave(&cfspi->lock, flags);
239 if (cfspi->cmd == SPI_CMD_EOT && !cfspi_xmitlen(cfspi)
240 && !test_bit(SPI_SS_ON, &cfspi->state))
241 clear_bit(SPI_XFER, &cfspi->state);
242
243 spin_unlock_irqrestore(&cfspi->lock, flags);
244 }
245 }
246
247 struct platform_driver cfspi_spi_driver = {
248 .probe = cfspi_spi_probe,
249 .remove = cfspi_spi_remove,
250 .driver = {
251 .name = "cfspi_sspi",
252 .owner = THIS_MODULE,
253 },
254 };
255
