1 /* 2 * STM32L4x5 SoC family 3 * 4 * Copyright (c) 2023 Arnaud Minier <arnaud.minier@telecom-paris.fr> 5 * Copyright (c) 2023 Inès Varhol <ines.varhol@telecom-paris.fr> 6 * 7 * SPDX-License-Identifier: GPL-2.0-or-later 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2 or later. 10 * See the COPYING file in the top-level directory. 11 * 12 * This work is heavily inspired by the stm32f405_soc by Alistair Francis. 13 * Original code is licensed under the MIT License: 14 * 15 * Copyright (c) 2014 Alistair Francis <alistair@alistair23.me> 16 */ 17 18 /* 19 * The reference used is the STMicroElectronics RM0351 Reference manual 20 * for STM32L4x5 and STM32L4x6 advanced Arm ® -based 32-bit MCUs. 21 * https://www.st.com/en/microcontrollers-microprocessors/stm32l4x5/documentation.html 22 */ 23 24 #include "qemu/osdep.h" 25 #include "qemu/units.h" 26 #include "qapi/error.h" 27 #include "exec/address-spaces.h" 28 #include "sysemu/sysemu.h" 29 #include "hw/or-irq.h" 30 #include "hw/arm/stm32l4x5_soc.h" 31 #include "hw/char/stm32l4x5_usart.h" 32 #include "hw/gpio/stm32l4x5_gpio.h" 33 #include "hw/qdev-clock.h" 34 #include "hw/misc/unimp.h" 35 36 #define FLASH_BASE_ADDRESS 0x08000000 37 #define SRAM1_BASE_ADDRESS 0x20000000 38 #define SRAM1_SIZE (96 * KiB) 39 #define SRAM2_BASE_ADDRESS 0x10000000 40 #define SRAM2_SIZE (32 * KiB) 41 42 #define EXTI_ADDR 0x40010400 43 #define SYSCFG_ADDR 0x40010000 44 45 #define NUM_EXTI_IRQ 40 46 /* Match exti line connections with their CPU IRQ number */ 47 /* See Vector Table (Reference Manual p.396) */ 48 /* 49 * Some IRQs are connected to the same CPU IRQ (denoted by -1) 50 * and require an intermediary OR gate to function correctly. 51 */ 52 static const int exti_irq[NUM_EXTI_IRQ] = { 53 6, /* GPIO[0] */ 54 7, /* GPIO[1] */ 55 8, /* GPIO[2] */ 56 9, /* GPIO[3] */ 57 10, /* GPIO[4] */ 58 -1, -1, -1, -1, -1, /* GPIO[5..9] OR gate 23 */ 59 -1, -1, -1, -1, -1, -1, /* GPIO[10..15] OR gate 40 */ 60 -1, /* PVD OR gate 1 */ 61 67, /* OTG_FS_WKUP, Direct */ 62 41, /* RTC_ALARM */ 63 2, /* RTC_TAMP_STAMP2/CSS_LSE */ 64 3, /* RTC wakeup timer */ 65 -1, -1, /* COMP[1..2] OR gate 63 */ 66 31, /* I2C1 wakeup, Direct */ 67 33, /* I2C2 wakeup, Direct */ 68 72, /* I2C3 wakeup, Direct */ 69 37, /* USART1 wakeup, Direct */ 70 38, /* USART2 wakeup, Direct */ 71 39, /* USART3 wakeup, Direct */ 72 52, /* UART4 wakeup, Direct */ 73 53, /* UART4 wakeup, Direct */ 74 70, /* LPUART1 wakeup, Direct */ 75 65, /* LPTIM1, Direct */ 76 66, /* LPTIM2, Direct */ 77 76, /* SWPMI1 wakeup, Direct */ 78 -1, -1, -1, -1, /* PVM[1..4] OR gate 1 */ 79 78 /* LCD wakeup, Direct */ 80 }; 81 #define RCC_BASE_ADDRESS 0x40021000 82 #define RCC_IRQ 5 83 84 static const int exti_or_gates_out[NUM_EXTI_OR_GATES] = { 85 23, 40, 63, 1, 86 }; 87 88 static const int exti_or_gates_num_lines_in[NUM_EXTI_OR_GATES] = { 89 5, 6, 2, 5, 90 }; 91 92 /* 3 OR gates with consecutive inputs */ 93 #define NUM_EXTI_SIMPLE_OR_GATES 3 94 static const int exti_or_gates_first_line_in[NUM_EXTI_SIMPLE_OR_GATES] = { 95 5, 10, 21, 96 }; 97 98 /* 1 OR gate with non-consecutive inputs */ 99 #define EXTI_OR_GATE1_NUM_LINES_IN 5 100 static const int exti_or_gate1_lines_in[EXTI_OR_GATE1_NUM_LINES_IN] = { 101 16, 35, 36, 37, 38, 102 }; 103 104 static const struct { 105 uint32_t addr; 106 uint32_t moder_reset; 107 uint32_t ospeedr_reset; 108 uint32_t pupdr_reset; 109 } stm32l4x5_gpio_cfg[NUM_GPIOS] = { 110 { 0x48000000, 0xABFFFFFF, 0x0C000000, 0x64000000 }, 111 { 0x48000400, 0xFFFFFEBF, 0x00000000, 0x00000100 }, 112 { 0x48000800, 0xFFFFFFFF, 0x00000000, 0x00000000 }, 113 { 0x48000C00, 0xFFFFFFFF, 0x00000000, 0x00000000 }, 114 { 0x48001000, 0xFFFFFFFF, 0x00000000, 0x00000000 }, 115 { 0x48001400, 0xFFFFFFFF, 0x00000000, 0x00000000 }, 116 { 0x48001800, 0xFFFFFFFF, 0x00000000, 0x00000000 }, 117 { 0x48001C00, 0x0000000F, 0x00000000, 0x00000000 }, 118 }; 119 120 static const hwaddr usart_addr[] = { 121 0x40013800, /* "USART1", 0x400 */ 122 0x40004400, /* "USART2", 0x400 */ 123 0x40004800, /* "USART3", 0x400 */ 124 }; 125 static const hwaddr uart_addr[] = { 126 0x40004C00, /* "UART4" , 0x400 */ 127 0x40005000 /* "UART5" , 0x400 */ 128 }; 129 130 #define LPUART_BASE_ADDRESS 0x40008000 131 132 static const int usart_irq[] = { 37, 38, 39 }; 133 static const int uart_irq[] = { 52, 53 }; 134 #define LPUART_IRQ 70 135 136 static void stm32l4x5_soc_initfn(Object *obj) 137 { 138 Stm32l4x5SocState *s = STM32L4X5_SOC(obj); 139 140 object_initialize_child(obj, "exti", &s->exti, TYPE_STM32L4X5_EXTI); 141 for (unsigned i = 0; i < NUM_EXTI_OR_GATES; i++) { 142 object_initialize_child(obj, "exti_or_gates[*]", &s->exti_or_gates[i], 143 TYPE_OR_IRQ); 144 } 145 object_initialize_child(obj, "syscfg", &s->syscfg, TYPE_STM32L4X5_SYSCFG); 146 object_initialize_child(obj, "rcc", &s->rcc, TYPE_STM32L4X5_RCC); 147 148 for (unsigned i = 0; i < NUM_GPIOS; i++) { 149 g_autofree char *name = g_strdup_printf("gpio%c", 'a' + i); 150 object_initialize_child(obj, name, &s->gpio[i], TYPE_STM32L4X5_GPIO); 151 } 152 153 for (int i = 0; i < STM_NUM_USARTS; i++) { 154 object_initialize_child(obj, "usart[*]", &s->usart[i], 155 TYPE_STM32L4X5_USART); 156 } 157 158 for (int i = 0; i < STM_NUM_UARTS; i++) { 159 object_initialize_child(obj, "uart[*]", &s->uart[i], 160 TYPE_STM32L4X5_UART); 161 } 162 object_initialize_child(obj, "lpuart1", &s->lpuart, 163 TYPE_STM32L4X5_LPUART); 164 } 165 166 static void stm32l4x5_soc_realize(DeviceState *dev_soc, Error **errp) 167 { 168 ERRP_GUARD(); 169 Stm32l4x5SocState *s = STM32L4X5_SOC(dev_soc); 170 const Stm32l4x5SocClass *sc = STM32L4X5_SOC_GET_CLASS(dev_soc); 171 MemoryRegion *system_memory = get_system_memory(); 172 DeviceState *armv7m, *dev; 173 SysBusDevice *busdev; 174 uint32_t pin_index; 175 176 if (!memory_region_init_rom(&s->flash, OBJECT(dev_soc), "flash", 177 sc->flash_size, errp)) { 178 return; 179 } 180 memory_region_init_alias(&s->flash_alias, OBJECT(dev_soc), 181 "flash_boot_alias", &s->flash, 0, 182 sc->flash_size); 183 184 memory_region_add_subregion(system_memory, FLASH_BASE_ADDRESS, &s->flash); 185 memory_region_add_subregion(system_memory, 0, &s->flash_alias); 186 187 if (!memory_region_init_ram(&s->sram1, OBJECT(dev_soc), "SRAM1", SRAM1_SIZE, 188 errp)) { 189 return; 190 } 191 memory_region_add_subregion(system_memory, SRAM1_BASE_ADDRESS, &s->sram1); 192 193 if (!memory_region_init_ram(&s->sram2, OBJECT(dev_soc), "SRAM2", SRAM2_SIZE, 194 errp)) { 195 return; 196 } 197 memory_region_add_subregion(system_memory, SRAM2_BASE_ADDRESS, &s->sram2); 198 199 object_initialize_child(OBJECT(dev_soc), "armv7m", &s->armv7m, TYPE_ARMV7M); 200 armv7m = DEVICE(&s->armv7m); 201 qdev_prop_set_uint32(armv7m, "num-irq", 96); 202 qdev_prop_set_uint32(armv7m, "num-prio-bits", 4); 203 qdev_prop_set_string(armv7m, "cpu-type", ARM_CPU_TYPE_NAME("cortex-m4")); 204 qdev_prop_set_bit(armv7m, "enable-bitband", true); 205 qdev_connect_clock_in(armv7m, "cpuclk", 206 qdev_get_clock_out(DEVICE(&(s->rcc)), "cortex-fclk-out")); 207 qdev_connect_clock_in(armv7m, "refclk", 208 qdev_get_clock_out(DEVICE(&(s->rcc)), "cortex-refclk-out")); 209 object_property_set_link(OBJECT(&s->armv7m), "memory", 210 OBJECT(system_memory), &error_abort); 211 if (!sysbus_realize(SYS_BUS_DEVICE(&s->armv7m), errp)) { 212 return; 213 } 214 215 /* GPIOs */ 216 for (unsigned i = 0; i < NUM_GPIOS; i++) { 217 g_autofree char *name = g_strdup_printf("%c", 'A' + i); 218 dev = DEVICE(&s->gpio[i]); 219 qdev_prop_set_string(dev, "name", name); 220 qdev_prop_set_uint32(dev, "mode-reset", 221 stm32l4x5_gpio_cfg[i].moder_reset); 222 qdev_prop_set_uint32(dev, "ospeed-reset", 223 stm32l4x5_gpio_cfg[i].ospeedr_reset); 224 qdev_prop_set_uint32(dev, "pupd-reset", 225 stm32l4x5_gpio_cfg[i].pupdr_reset); 226 busdev = SYS_BUS_DEVICE(&s->gpio[i]); 227 g_free(name); 228 name = g_strdup_printf("gpio%c-out", 'a' + i); 229 qdev_connect_clock_in(DEVICE(&s->gpio[i]), "clk", 230 qdev_get_clock_out(DEVICE(&(s->rcc)), name)); 231 if (!sysbus_realize(busdev, errp)) { 232 return; 233 } 234 sysbus_mmio_map(busdev, 0, stm32l4x5_gpio_cfg[i].addr); 235 } 236 237 /* System configuration controller */ 238 busdev = SYS_BUS_DEVICE(&s->syscfg); 239 if (!sysbus_realize(busdev, errp)) { 240 return; 241 } 242 sysbus_mmio_map(busdev, 0, SYSCFG_ADDR); 243 244 for (unsigned i = 0; i < NUM_GPIOS; i++) { 245 for (unsigned j = 0; j < GPIO_NUM_PINS; j++) { 246 pin_index = GPIO_NUM_PINS * i + j; 247 qdev_connect_gpio_out(DEVICE(&s->gpio[i]), j, 248 qdev_get_gpio_in(DEVICE(&s->syscfg), 249 pin_index)); 250 } 251 } 252 253 /* EXTI device */ 254 busdev = SYS_BUS_DEVICE(&s->exti); 255 if (!sysbus_realize(busdev, errp)) { 256 return; 257 } 258 sysbus_mmio_map(busdev, 0, EXTI_ADDR); 259 260 /* IRQs with fan-in that require an OR gate */ 261 for (unsigned i = 0; i < NUM_EXTI_OR_GATES; i++) { 262 if (!object_property_set_int(OBJECT(&s->exti_or_gates[i]), "num-lines", 263 exti_or_gates_num_lines_in[i], errp)) { 264 return; 265 } 266 if (!qdev_realize(DEVICE(&s->exti_or_gates[i]), NULL, errp)) { 267 return; 268 } 269 270 qdev_connect_gpio_out(DEVICE(&s->exti_or_gates[i]), 0, 271 qdev_get_gpio_in(armv7m, exti_or_gates_out[i])); 272 273 if (i < NUM_EXTI_SIMPLE_OR_GATES) { 274 /* consecutive inputs for OR gates 23, 40, 63 */ 275 for (unsigned j = 0; j < exti_or_gates_num_lines_in[i]; j++) { 276 sysbus_connect_irq(SYS_BUS_DEVICE(&s->exti), 277 exti_or_gates_first_line_in[i] + j, 278 qdev_get_gpio_in(DEVICE(&s->exti_or_gates[i]), j)); 279 } 280 } else { 281 /* non-consecutive inputs for OR gate 1 */ 282 for (unsigned j = 0; j < EXTI_OR_GATE1_NUM_LINES_IN; j++) { 283 sysbus_connect_irq(SYS_BUS_DEVICE(&s->exti), 284 exti_or_gate1_lines_in[j], 285 qdev_get_gpio_in(DEVICE(&s->exti_or_gates[i]), j)); 286 } 287 } 288 } 289 290 /* IRQs that don't require fan-in */ 291 for (unsigned i = 0; i < NUM_EXTI_IRQ; i++) { 292 if (exti_irq[i] != -1) { 293 sysbus_connect_irq(busdev, i, 294 qdev_get_gpio_in(armv7m, exti_irq[i])); 295 } 296 } 297 298 for (unsigned i = 0; i < GPIO_NUM_PINS; i++) { 299 qdev_connect_gpio_out(DEVICE(&s->syscfg), i, 300 qdev_get_gpio_in(DEVICE(&s->exti), i)); 301 } 302 303 /* RCC device */ 304 busdev = SYS_BUS_DEVICE(&s->rcc); 305 if (!sysbus_realize(busdev, errp)) { 306 return; 307 } 308 sysbus_mmio_map(busdev, 0, RCC_BASE_ADDRESS); 309 sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, RCC_IRQ)); 310 311 /* USART devices */ 312 for (int i = 0; i < STM_NUM_USARTS; i++) { 313 g_autofree char *name = g_strdup_printf("usart%d-out", i + 1); 314 dev = DEVICE(&(s->usart[i])); 315 qdev_prop_set_chr(dev, "chardev", serial_hd(i)); 316 qdev_connect_clock_in(dev, "clk", 317 qdev_get_clock_out(DEVICE(&(s->rcc)), name)); 318 busdev = SYS_BUS_DEVICE(dev); 319 if (!sysbus_realize(busdev, errp)) { 320 return; 321 } 322 sysbus_mmio_map(busdev, 0, usart_addr[i]); 323 sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, usart_irq[i])); 324 } 325 326 /* 327 * TODO: Connect the USARTs, UARTs and LPUART to the EXTI once the EXTI 328 * can handle other gpio-in than the gpios. (e.g. Direct Lines for the 329 * usarts) 330 */ 331 332 /* UART devices */ 333 for (int i = 0; i < STM_NUM_UARTS; i++) { 334 g_autofree char *name = g_strdup_printf("uart%d-out", STM_NUM_USARTS + i + 1); 335 dev = DEVICE(&(s->uart[i])); 336 qdev_prop_set_chr(dev, "chardev", serial_hd(STM_NUM_USARTS + i)); 337 qdev_connect_clock_in(dev, "clk", 338 qdev_get_clock_out(DEVICE(&(s->rcc)), name)); 339 busdev = SYS_BUS_DEVICE(dev); 340 if (!sysbus_realize(busdev, errp)) { 341 return; 342 } 343 sysbus_mmio_map(busdev, 0, uart_addr[i]); 344 sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, uart_irq[i])); 345 } 346 347 /* LPUART device*/ 348 dev = DEVICE(&(s->lpuart)); 349 qdev_prop_set_chr(dev, "chardev", serial_hd(STM_NUM_USARTS + STM_NUM_UARTS)); 350 qdev_connect_clock_in(dev, "clk", 351 qdev_get_clock_out(DEVICE(&(s->rcc)), "lpuart1-out")); 352 busdev = SYS_BUS_DEVICE(dev); 353 if (!sysbus_realize(busdev, errp)) { 354 return; 355 } 356 sysbus_mmio_map(busdev, 0, LPUART_BASE_ADDRESS); 357 sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, LPUART_IRQ)); 358 359 /* APB1 BUS */ 360 create_unimplemented_device("TIM2", 0x40000000, 0x400); 361 create_unimplemented_device("TIM3", 0x40000400, 0x400); 362 create_unimplemented_device("TIM4", 0x40000800, 0x400); 363 create_unimplemented_device("TIM5", 0x40000C00, 0x400); 364 create_unimplemented_device("TIM6", 0x40001000, 0x400); 365 create_unimplemented_device("TIM7", 0x40001400, 0x400); 366 /* RESERVED: 0x40001800, 0x1000 */ 367 create_unimplemented_device("RTC", 0x40002800, 0x400); 368 create_unimplemented_device("WWDG", 0x40002C00, 0x400); 369 create_unimplemented_device("IWDG", 0x40003000, 0x400); 370 /* RESERVED: 0x40001800, 0x400 */ 371 create_unimplemented_device("SPI2", 0x40003800, 0x400); 372 create_unimplemented_device("SPI3", 0x40003C00, 0x400); 373 /* RESERVED: 0x40004000, 0x400 */ 374 create_unimplemented_device("I2C1", 0x40005400, 0x400); 375 create_unimplemented_device("I2C2", 0x40005800, 0x400); 376 create_unimplemented_device("I2C3", 0x40005C00, 0x400); 377 /* RESERVED: 0x40006000, 0x400 */ 378 create_unimplemented_device("CAN1", 0x40006400, 0x400); 379 /* RESERVED: 0x40006800, 0x400 */ 380 create_unimplemented_device("PWR", 0x40007000, 0x400); 381 create_unimplemented_device("DAC1", 0x40007400, 0x400); 382 create_unimplemented_device("OPAMP", 0x40007800, 0x400); 383 create_unimplemented_device("LPTIM1", 0x40007C00, 0x400); 384 /* RESERVED: 0x40008400, 0x400 */ 385 create_unimplemented_device("SWPMI1", 0x40008800, 0x400); 386 /* RESERVED: 0x40008C00, 0x800 */ 387 create_unimplemented_device("LPTIM2", 0x40009400, 0x400); 388 /* RESERVED: 0x40009800, 0x6800 */ 389 390 /* APB2 BUS */ 391 create_unimplemented_device("VREFBUF", 0x40010030, 0x1D0); 392 create_unimplemented_device("COMP", 0x40010200, 0x200); 393 /* RESERVED: 0x40010800, 0x1400 */ 394 create_unimplemented_device("FIREWALL", 0x40011C00, 0x400); 395 /* RESERVED: 0x40012000, 0x800 */ 396 create_unimplemented_device("SDMMC1", 0x40012800, 0x400); 397 create_unimplemented_device("TIM1", 0x40012C00, 0x400); 398 create_unimplemented_device("SPI1", 0x40013000, 0x400); 399 create_unimplemented_device("TIM8", 0x40013400, 0x400); 400 /* RESERVED: 0x40013C00, 0x400 */ 401 create_unimplemented_device("TIM15", 0x40014000, 0x400); 402 create_unimplemented_device("TIM16", 0x40014400, 0x400); 403 create_unimplemented_device("TIM17", 0x40014800, 0x400); 404 /* RESERVED: 0x40014C00, 0x800 */ 405 create_unimplemented_device("SAI1", 0x40015400, 0x400); 406 create_unimplemented_device("SAI2", 0x40015800, 0x400); 407 /* RESERVED: 0x40015C00, 0x400 */ 408 create_unimplemented_device("DFSDM1", 0x40016000, 0x400); 409 /* RESERVED: 0x40016400, 0x9C00 */ 410 411 /* AHB1 BUS */ 412 create_unimplemented_device("DMA1", 0x40020000, 0x400); 413 create_unimplemented_device("DMA2", 0x40020400, 0x400); 414 /* RESERVED: 0x40020800, 0x800 */ 415 /* RESERVED: 0x40021400, 0xC00 */ 416 create_unimplemented_device("FLASH", 0x40022000, 0x400); 417 /* RESERVED: 0x40022400, 0xC00 */ 418 create_unimplemented_device("CRC", 0x40023000, 0x400); 419 /* RESERVED: 0x40023400, 0x400 */ 420 create_unimplemented_device("TSC", 0x40024000, 0x400); 421 422 /* RESERVED: 0x40024400, 0x7FDBC00 */ 423 424 /* AHB2 BUS */ 425 /* RESERVED: 0x48002000, 0x7FDBC00 */ 426 create_unimplemented_device("OTG_FS", 0x50000000, 0x40000); 427 create_unimplemented_device("ADC", 0x50040000, 0x400); 428 /* RESERVED: 0x50040400, 0x20400 */ 429 create_unimplemented_device("RNG", 0x50060800, 0x400); 430 431 /* AHB3 BUS */ 432 create_unimplemented_device("FMC", 0xA0000000, 0x1000); 433 create_unimplemented_device("QUADSPI", 0xA0001000, 0x400); 434 } 435 436 static void stm32l4x5_soc_class_init(ObjectClass *klass, void *data) 437 { 438 439 DeviceClass *dc = DEVICE_CLASS(klass); 440 441 dc->realize = stm32l4x5_soc_realize; 442 /* Reason: Mapped at fixed location on the system bus */ 443 dc->user_creatable = false; 444 /* No vmstate or reset required: device has no internal state */ 445 } 446 447 static void stm32l4x5xc_soc_class_init(ObjectClass *oc, void *data) 448 { 449 Stm32l4x5SocClass *ssc = STM32L4X5_SOC_CLASS(oc); 450 451 ssc->flash_size = 256 * KiB; 452 } 453 454 static void stm32l4x5xe_soc_class_init(ObjectClass *oc, void *data) 455 { 456 Stm32l4x5SocClass *ssc = STM32L4X5_SOC_CLASS(oc); 457 458 ssc->flash_size = 512 * KiB; 459 } 460 461 static void stm32l4x5xg_soc_class_init(ObjectClass *oc, void *data) 462 { 463 Stm32l4x5SocClass *ssc = STM32L4X5_SOC_CLASS(oc); 464 465 ssc->flash_size = 1 * MiB; 466 } 467 468 static const TypeInfo stm32l4x5_soc_types[] = { 469 { 470 .name = TYPE_STM32L4X5XC_SOC, 471 .parent = TYPE_STM32L4X5_SOC, 472 .class_init = stm32l4x5xc_soc_class_init, 473 }, { 474 .name = TYPE_STM32L4X5XE_SOC, 475 .parent = TYPE_STM32L4X5_SOC, 476 .class_init = stm32l4x5xe_soc_class_init, 477 }, { 478 .name = TYPE_STM32L4X5XG_SOC, 479 .parent = TYPE_STM32L4X5_SOC, 480 .class_init = stm32l4x5xg_soc_class_init, 481 }, { 482 .name = TYPE_STM32L4X5_SOC, 483 .parent = TYPE_SYS_BUS_DEVICE, 484 .instance_size = sizeof(Stm32l4x5SocState), 485 .instance_init = stm32l4x5_soc_initfn, 486 .class_size = sizeof(Stm32l4x5SocClass), 487 .class_init = stm32l4x5_soc_class_init, 488 .abstract = true, 489 } 490 }; 491 492 DEFINE_TYPES(stm32l4x5_soc_types) 493