1 /* 2 * BCM2835 SPI Master Controller 3 * 4 * Copyright (c) 2024 Rayhan Faizel <rayhan.faizel@gmail.com> 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 #include "qemu/osdep.h" 26 #include "qemu/log.h" 27 #include "qemu/fifo8.h" 28 #include "hw/ssi/bcm2835_spi.h" 29 #include "hw/irq.h" 30 #include "migration/vmstate.h" 31 32 static void bcm2835_spi_update_int(BCM2835SPIState *s) 33 { 34 int do_interrupt = 0; 35 36 /* Interrupt on DONE */ 37 if (s->cs & BCM2835_SPI_CS_INTD && s->cs & BCM2835_SPI_CS_DONE) { 38 do_interrupt = 1; 39 } 40 /* Interrupt on RXR */ 41 if (s->cs & BCM2835_SPI_CS_INTR && s->cs & BCM2835_SPI_CS_RXR) { 42 do_interrupt = 1; 43 } 44 qemu_set_irq(s->irq, do_interrupt); 45 } 46 47 static void bcm2835_spi_update_rx_flags(BCM2835SPIState *s) 48 { 49 /* Set RXD if RX FIFO is non empty */ 50 if (!fifo8_is_empty(&s->rx_fifo)) { 51 s->cs |= BCM2835_SPI_CS_RXD; 52 } else { 53 s->cs &= ~BCM2835_SPI_CS_RXD; 54 } 55 56 /* Set RXF if RX FIFO is full */ 57 if (fifo8_is_full(&s->rx_fifo)) { 58 s->cs |= BCM2835_SPI_CS_RXF; 59 } else { 60 s->cs &= ~BCM2835_SPI_CS_RXF; 61 } 62 63 /* Set RXR if RX FIFO is 3/4th used or above */ 64 if (fifo8_num_used(&s->rx_fifo) >= FIFO_SIZE_3_4) { 65 s->cs |= BCM2835_SPI_CS_RXR; 66 } else { 67 s->cs &= ~BCM2835_SPI_CS_RXR; 68 } 69 } 70 71 static void bcm2835_spi_update_tx_flags(BCM2835SPIState *s) 72 { 73 /* Set TXD if TX FIFO is not full */ 74 if (fifo8_is_full(&s->tx_fifo)) { 75 s->cs &= ~BCM2835_SPI_CS_TXD; 76 } else { 77 s->cs |= BCM2835_SPI_CS_TXD; 78 } 79 80 /* Set DONE if in TA mode and TX FIFO is empty */ 81 if (fifo8_is_empty(&s->tx_fifo) && s->cs & BCM2835_SPI_CS_TA) { 82 s->cs |= BCM2835_SPI_CS_DONE; 83 } else { 84 s->cs &= ~BCM2835_SPI_CS_DONE; 85 } 86 } 87 88 static void bcm2835_spi_flush_tx_fifo(BCM2835SPIState *s) 89 { 90 uint8_t tx_byte, rx_byte; 91 92 while (!fifo8_is_empty(&s->tx_fifo) && !fifo8_is_full(&s->rx_fifo)) { 93 tx_byte = fifo8_pop(&s->tx_fifo); 94 rx_byte = ssi_transfer(s->bus, tx_byte); 95 fifo8_push(&s->rx_fifo, rx_byte); 96 } 97 98 bcm2835_spi_update_tx_flags(s); 99 bcm2835_spi_update_rx_flags(s); 100 } 101 102 static uint64_t bcm2835_spi_read(void *opaque, hwaddr addr, unsigned size) 103 { 104 BCM2835SPIState *s = opaque; 105 uint32_t readval = 0; 106 107 switch (addr) { 108 case BCM2835_SPI_CS: 109 readval = s->cs & 0xffffffff; 110 break; 111 case BCM2835_SPI_FIFO: 112 bcm2835_spi_flush_tx_fifo(s); 113 if (s->cs & BCM2835_SPI_CS_RXD) { 114 readval = fifo8_pop(&s->rx_fifo); 115 bcm2835_spi_update_rx_flags(s); 116 } 117 118 bcm2835_spi_update_int(s); 119 break; 120 case BCM2835_SPI_CLK: 121 readval = s->clk & 0xffff; 122 break; 123 case BCM2835_SPI_DLEN: 124 readval = s->dlen & 0xffff; 125 break; 126 case BCM2835_SPI_LTOH: 127 readval = s->ltoh & 0xf; 128 break; 129 case BCM2835_SPI_DC: 130 readval = s->dc & 0xffffffff; 131 break; 132 default: 133 qemu_log_mask(LOG_GUEST_ERROR, 134 "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, addr); 135 } 136 return readval; 137 } 138 139 static void bcm2835_spi_write(void *opaque, hwaddr addr, 140 uint64_t value, unsigned int size) 141 { 142 BCM2835SPIState *s = opaque; 143 144 switch (addr) { 145 case BCM2835_SPI_CS: 146 s->cs = (value & ~RO_MASK) | (s->cs & RO_MASK); 147 if (!(s->cs & BCM2835_SPI_CS_TA)) { 148 /* Clear DONE and RXR if TA is off */ 149 s->cs &= ~(BCM2835_SPI_CS_DONE); 150 s->cs &= ~(BCM2835_SPI_CS_RXR); 151 } 152 153 /* Clear RX FIFO */ 154 if (s->cs & BCM2835_SPI_CLEAR_RX) { 155 fifo8_reset(&s->rx_fifo); 156 bcm2835_spi_update_rx_flags(s); 157 } 158 159 /* Clear TX FIFO*/ 160 if (s->cs & BCM2835_SPI_CLEAR_TX) { 161 fifo8_reset(&s->tx_fifo); 162 bcm2835_spi_update_tx_flags(s); 163 } 164 165 /* Set Transfer Active */ 166 if (s->cs & BCM2835_SPI_CS_TA) { 167 bcm2835_spi_update_tx_flags(s); 168 } 169 170 if (s->cs & BCM2835_SPI_CS_DMAEN) { 171 qemu_log_mask(LOG_UNIMP, "%s: " \ 172 "DMA not supported\n", __func__); 173 } 174 175 if (s->cs & BCM2835_SPI_CS_LEN) { 176 qemu_log_mask(LOG_UNIMP, "%s: " \ 177 "LoSSI not supported\n", __func__); 178 } 179 180 bcm2835_spi_update_int(s); 181 break; 182 case BCM2835_SPI_FIFO: 183 /* 184 * According to documentation, writes to FIFO without TA controls 185 * CS and DLEN registers. This is supposed to be used in DMA mode 186 * which is currently unimplemented. Moreover, Linux does not make 187 * use of this and directly modifies the CS and DLEN registers. 188 */ 189 if (s->cs & BCM2835_SPI_CS_TA) { 190 if (s->cs & BCM2835_SPI_CS_TXD) { 191 fifo8_push(&s->tx_fifo, value & 0xff); 192 bcm2835_spi_update_tx_flags(s); 193 } 194 195 bcm2835_spi_flush_tx_fifo(s); 196 bcm2835_spi_update_int(s); 197 } 198 break; 199 case BCM2835_SPI_CLK: 200 s->clk = value & 0xffff; 201 break; 202 case BCM2835_SPI_DLEN: 203 s->dlen = value & 0xffff; 204 break; 205 case BCM2835_SPI_LTOH: 206 s->ltoh = value & 0xf; 207 break; 208 case BCM2835_SPI_DC: 209 s->dc = value & 0xffffffff; 210 break; 211 default: 212 qemu_log_mask(LOG_GUEST_ERROR, 213 "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, addr); 214 } 215 } 216 217 static const MemoryRegionOps bcm2835_spi_ops = { 218 .read = bcm2835_spi_read, 219 .write = bcm2835_spi_write, 220 .endianness = DEVICE_NATIVE_ENDIAN, 221 }; 222 223 static void bcm2835_spi_realize(DeviceState *dev, Error **errp) 224 { 225 BCM2835SPIState *s = BCM2835_SPI(dev); 226 s->bus = ssi_create_bus(dev, "spi"); 227 228 memory_region_init_io(&s->iomem, OBJECT(dev), &bcm2835_spi_ops, s, 229 TYPE_BCM2835_SPI, 0x18); 230 sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->iomem); 231 sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq); 232 233 fifo8_create(&s->tx_fifo, FIFO_SIZE); 234 fifo8_create(&s->rx_fifo, FIFO_SIZE); 235 } 236 static void bcm2835_spi_reset(DeviceState *dev) 237 { 238 BCM2835SPIState *s = BCM2835_SPI(dev); 239 240 fifo8_reset(&s->tx_fifo); 241 fifo8_reset(&s->rx_fifo); 242 243 /* Reset values according to BCM2835 Peripheral Documentation */ 244 s->cs = BCM2835_SPI_CS_TXD | BCM2835_SPI_CS_REN; 245 s->clk = 0; 246 s->dlen = 0; 247 s->ltoh = 0x1; 248 s->dc = 0x30201020; 249 } 250 251 static const VMStateDescription vmstate_bcm2835_spi = { 252 .name = TYPE_BCM2835_SPI, 253 .version_id = 1, 254 .minimum_version_id = 1, 255 .fields = (const VMStateField[]) { 256 VMSTATE_FIFO8(tx_fifo, BCM2835SPIState), 257 VMSTATE_FIFO8(rx_fifo, BCM2835SPIState), 258 VMSTATE_UINT32(cs, BCM2835SPIState), 259 VMSTATE_UINT32(clk, BCM2835SPIState), 260 VMSTATE_UINT32(dlen, BCM2835SPIState), 261 VMSTATE_UINT32(ltoh, BCM2835SPIState), 262 VMSTATE_UINT32(dc, BCM2835SPIState), 263 VMSTATE_END_OF_LIST() 264 } 265 }; 266 267 static void bcm2835_spi_class_init(ObjectClass *klass, void *data) 268 { 269 DeviceClass *dc = DEVICE_CLASS(klass); 270 271 dc->reset = bcm2835_spi_reset; 272 dc->realize = bcm2835_spi_realize; 273 dc->vmsd = &vmstate_bcm2835_spi; 274 } 275 276 static const TypeInfo bcm2835_spi_info = { 277 .name = TYPE_BCM2835_SPI, 278 .parent = TYPE_SYS_BUS_DEVICE, 279 .instance_size = sizeof(BCM2835SPIState), 280 .class_init = bcm2835_spi_class_init, 281 }; 282 283 static void bcm2835_spi_register_types(void) 284 { 285 type_register_static(&bcm2835_spi_info); 286 } 287 288 type_init(bcm2835_spi_register_types) 289