xref: /openbmc/qemu/hw/ssi/sifive_spi.c (revision 8f968b6a) 
1 /*
2  * QEMU model of the SiFive SPI Controller
3  *
4  * Copyright (c) 2021 Wind River Systems, Inc.
5  *
6  * Author:
7  *   Bin Meng <bin.meng@windriver.com>
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms and conditions of the GNU General Public License,
11  * version 2 or later, as published by the Free Software Foundation.
12  *
13  * This program is distributed in the hope it will be useful, but WITHOUT
14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
16  * more details.
17  *
18  * You should have received a copy of the GNU General Public License along with
19  * this program.  If not, see <http://www.gnu.org/licenses/>.
20  */
21 
22 #include "qemu/osdep.h"
23 #include "hw/irq.h"
24 #include "hw/qdev-properties.h"
25 #include "hw/sysbus.h"
26 #include "hw/ssi/ssi.h"
27 #include "qemu/fifo8.h"
28 #include "qemu/log.h"
29 #include "qemu/module.h"
30 #include "hw/ssi/sifive_spi.h"
31 
32 #define R_SCKDIV        (0x00 / 4)
33 #define R_SCKMODE       (0x04 / 4)
34 #define R_CSID          (0x10 / 4)
35 #define R_CSDEF         (0x14 / 4)
36 #define R_CSMODE        (0x18 / 4)
37 #define R_DELAY0        (0x28 / 4)
38 #define R_DELAY1        (0x2C / 4)
39 #define R_FMT           (0x40 / 4)
40 #define R_TXDATA        (0x48 / 4)
41 #define R_RXDATA        (0x4C / 4)
42 #define R_TXMARK        (0x50 / 4)
43 #define R_RXMARK        (0x54 / 4)
44 #define R_FCTRL         (0x60 / 4)
45 #define R_FFMT          (0x64 / 4)
46 #define R_IE            (0x70 / 4)
47 #define R_IP            (0x74 / 4)
48 
49 #define FMT_DIR         (1 << 3)
50 
51 #define TXDATA_FULL     (1 << 31)
52 #define RXDATA_EMPTY    (1 << 31)
53 
54 #define IE_TXWM         (1 << 0)
55 #define IE_RXWM         (1 << 1)
56 
57 #define IP_TXWM         (1 << 0)
58 #define IP_RXWM         (1 << 1)
59 
60 #define FIFO_CAPACITY   8
61 
62 static void sifive_spi_txfifo_reset(SiFiveSPIState *s)
63 {
64     fifo8_reset(&s->tx_fifo);
65 
66     s->regs[R_TXDATA] &= ~TXDATA_FULL;
67     s->regs[R_IP] &= ~IP_TXWM;
68 }
69 
70 static void sifive_spi_rxfifo_reset(SiFiveSPIState *s)
71 {
72     fifo8_reset(&s->rx_fifo);
73 
74     s->regs[R_RXDATA] |= RXDATA_EMPTY;
75     s->regs[R_IP] &= ~IP_RXWM;
76 }
77 
78 static void sifive_spi_update_cs(SiFiveSPIState *s)
79 {
80     int i;
81 
82     for (i = 0; i < s->num_cs; i++) {
83         if (s->regs[R_CSDEF] & (1 << i)) {
84             qemu_set_irq(s->cs_lines[i], !(s->regs[R_CSMODE]));
85         }
86     }
87 }
88 
89 static void sifive_spi_update_irq(SiFiveSPIState *s)
90 {
91     int level;
92 
93     if (fifo8_num_used(&s->tx_fifo) < s->regs[R_TXMARK]) {
94         s->regs[R_IP] |= IP_TXWM;
95     } else {
96         s->regs[R_IP] &= ~IP_TXWM;
97     }
98 
99     if (fifo8_num_used(&s->rx_fifo) > s->regs[R_RXMARK]) {
100         s->regs[R_IP] |= IP_RXWM;
101     } else {
102         s->regs[R_IP] &= ~IP_RXWM;
103     }
104 
105     level = s->regs[R_IP] & s->regs[R_IE] ? 1 : 0;
106     qemu_set_irq(s->irq, level);
107 }
108 
109 static void sifive_spi_reset(DeviceState *d)
110 {
111     SiFiveSPIState *s = SIFIVE_SPI(d);
112 
113     memset(s->regs, 0, sizeof(s->regs));
114 
115     /* The reset value is high for all implemented CS pins */
116     s->regs[R_CSDEF] = (1 << s->num_cs) - 1;
117 
118     /* Populate register with their default value */
119     s->regs[R_SCKDIV] = 0x03;
120     s->regs[R_DELAY0] = 0x1001;
121     s->regs[R_DELAY1] = 0x01;
122 
123     sifive_spi_txfifo_reset(s);
124     sifive_spi_rxfifo_reset(s);
125 
126     sifive_spi_update_cs(s);
127     sifive_spi_update_irq(s);
128 }
129 
130 static void sifive_spi_flush_txfifo(SiFiveSPIState *s)
131 {
132     uint8_t tx;
133     uint8_t rx;
134 
135     while (!fifo8_is_empty(&s->tx_fifo)) {
136         tx = fifo8_pop(&s->tx_fifo);
137         rx = ssi_transfer(s->spi, tx);
138 
139         if (!fifo8_is_full(&s->rx_fifo)) {
140             if (!(s->regs[R_FMT] & FMT_DIR)) {
141                 fifo8_push(&s->rx_fifo, rx);
142             }
143         }
144     }
145 }
146 
147 static bool sifive_spi_is_bad_reg(hwaddr addr, bool allow_reserved)
148 {
149     bool bad;
150 
151     switch (addr) {
152     /* reserved offsets */
153     case 0x08:
154     case 0x0C:
155     case 0x1C:
156     case 0x20:
157     case 0x24:
158     case 0x30:
159     case 0x34:
160     case 0x38:
161     case 0x3C:
162     case 0x44:
163     case 0x58:
164     case 0x5C:
165     case 0x68:
166     case 0x6C:
167         bad = allow_reserved ? false : true;
168         break;
169     default:
170         bad = false;
171     }
172 
173     if (addr >= (SIFIVE_SPI_REG_NUM << 2)) {
174         bad = true;
175     }
176 
177     return bad;
178 }
179 
180 static uint64_t sifive_spi_read(void *opaque, hwaddr addr, unsigned int size)
181 {
182     SiFiveSPIState *s = opaque;
183     uint32_t r;
184 
185     if (sifive_spi_is_bad_reg(addr, true)) {
186         qemu_log_mask(LOG_GUEST_ERROR, "%s: bad read at address 0x%"
187                       HWADDR_PRIx "\n", __func__, addr);
188         return 0;
189     }
190 
191     addr >>= 2;
192     switch (addr) {
193     case R_TXDATA:
194         if (fifo8_is_full(&s->tx_fifo)) {
195             return TXDATA_FULL;
196         }
197         r = 0;
198         break;
199 
200     case R_RXDATA:
201         if (fifo8_is_empty(&s->rx_fifo)) {
202             return RXDATA_EMPTY;
203         }
204         r = fifo8_pop(&s->rx_fifo);
205         break;
206 
207     default:
208         r = s->regs[addr];
209         break;
210     }
211 
212     sifive_spi_update_irq(s);
213 
214     return r;
215 }
216 
217 static void sifive_spi_write(void *opaque, hwaddr addr,
218                              uint64_t val64, unsigned int size)
219 {
220     SiFiveSPIState *s = opaque;
221     uint32_t value = val64;
222 
223     if (sifive_spi_is_bad_reg(addr, false)) {
224         qemu_log_mask(LOG_GUEST_ERROR, "%s: bad write at addr=0x%"
225                       HWADDR_PRIx " value=0x%x\n", __func__, addr, value);
226         return;
227     }
228 
229     addr >>= 2;
230     switch (addr) {
231     case R_CSID:
232         if (value >= s->num_cs) {
233             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csid %d\n",
234                           __func__, value);
235         } else {
236             s->regs[R_CSID] = value;
237             sifive_spi_update_cs(s);
238         }
239         break;
240 
241     case R_CSDEF:
242         if (value >= (1 << s->num_cs)) {
243             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csdef %x\n",
244                           __func__, value);
245         } else {
246             s->regs[R_CSDEF] = value;
247         }
248         break;
249 
250     case R_CSMODE:
251         if (value > 3) {
252             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csmode %x\n",
253                           __func__, value);
254         } else {
255             s->regs[R_CSMODE] = value;
256             sifive_spi_update_cs(s);
257         }
258         break;
259 
260     case R_TXDATA:
261         if (!fifo8_is_full(&s->tx_fifo)) {
262             fifo8_push(&s->tx_fifo, (uint8_t)value);
263             sifive_spi_flush_txfifo(s);
264         }
265         break;
266 
267     case R_RXDATA:
268     case R_IP:
269         qemu_log_mask(LOG_GUEST_ERROR,
270                       "%s: invalid write to read-only reigster 0x%"
271                       HWADDR_PRIx " with 0x%x\n", __func__, addr << 2, value);
272         break;
273 
274     case R_TXMARK:
275     case R_RXMARK:
276         if (value >= FIFO_CAPACITY) {
277             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid watermark %d\n",
278                           __func__, value);
279         } else {
280             s->regs[addr] = value;
281         }
282         break;
283 
284     case R_FCTRL:
285     case R_FFMT:
286         qemu_log_mask(LOG_UNIMP,
287                       "%s: direct-map flash interface unimplemented\n",
288                       __func__);
289         break;
290 
291     default:
292         s->regs[addr] = value;
293         break;
294     }
295 
296     sifive_spi_update_irq(s);
297 }
298 
299 static const MemoryRegionOps sifive_spi_ops = {
300     .read = sifive_spi_read,
301     .write = sifive_spi_write,
302     .endianness = DEVICE_LITTLE_ENDIAN,
303     .valid = {
304         .min_access_size = 4,
305         .max_access_size = 4
306     }
307 };
308 
309 static void sifive_spi_realize(DeviceState *dev, Error **errp)
310 {
311     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
312     SiFiveSPIState *s = SIFIVE_SPI(dev);
313     int i;
314 
315     s->spi = ssi_create_bus(dev, "spi");
316     sysbus_init_irq(sbd, &s->irq);
317 
318     s->cs_lines = g_new0(qemu_irq, s->num_cs);
319     for (i = 0; i < s->num_cs; i++) {
320         sysbus_init_irq(sbd, &s->cs_lines[i]);
321     }
322 
323     memory_region_init_io(&s->mmio, OBJECT(s), &sifive_spi_ops, s,
324                           TYPE_SIFIVE_SPI, 0x1000);
325     sysbus_init_mmio(sbd, &s->mmio);
326 
327     fifo8_create(&s->tx_fifo, FIFO_CAPACITY);
328     fifo8_create(&s->rx_fifo, FIFO_CAPACITY);
329 }
330 
331 static Property sifive_spi_properties[] = {
332     DEFINE_PROP_UINT32("num-cs", SiFiveSPIState, num_cs, 1),
333     DEFINE_PROP_END_OF_LIST(),
334 };
335 
336 static void sifive_spi_class_init(ObjectClass *klass, void *data)
337 {
338     DeviceClass *dc = DEVICE_CLASS(klass);
339 
340     device_class_set_props(dc, sifive_spi_properties);
341     dc->reset = sifive_spi_reset;
342     dc->realize = sifive_spi_realize;
343 }
344 
345 static const TypeInfo sifive_spi_info = {
346     .name           = TYPE_SIFIVE_SPI,
347     .parent         = TYPE_SYS_BUS_DEVICE,
348     .instance_size  = sizeof(SiFiveSPIState),
349     .class_init     = sifive_spi_class_init,
350 };
351 
352 static void sifive_spi_register_types(void)
353 {
354     type_register_static(&sifive_spi_info);
355 }
356 
357 type_init(sifive_spi_register_types)
358