arch/arm/mach-ixp2000/core.c

   1 /*
   2  * arch/arm/mach-ixp2000/core.c
   3  *
   4  * Common routines used by all IXP2400/2800 based platforms.
   5  *
   6  * Author: Deepak Saxena <dsaxena@plexity.net>
   7  *
   8  * Copyright 2004 (C) MontaVista Software, Inc.
   9  *
  10  * Based on work Copyright (C) 2002-2003 Intel Corporation
  11  *
  12  * This file is licensed under the terms of the GNU General Public
  13  * License version 2. This program is licensed "as is" without any
  14  * warranty of any kind, whether express or implied.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/init.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/sched.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/irq.h>
  23 #include <linux/serial.h>
  24 #include <linux/tty.h>
  25 #include <linux/bitops.h>
  26 #include <linux/serial_8250.h>
  27 #include <linux/mm.h>
  28
  29 #include <asm/types.h>
  30 #include <asm/setup.h>
  31 #include <asm/memory.h>
  32 #include <mach/hardware.h>
  33 #include <asm/irq.h>
  34 #include <asm/system.h>
  35 #include <asm/tlbflush.h>
  36 #include <asm/pgtable.h>
  37
  38 #include <asm/mach/map.h>
  39 #include <asm/mach/time.h>
  40 #include <asm/mach/irq.h>
  41
  42 #include <mach/gpio.h>
  43
  44 static DEFINE_SPINLOCK(ixp2000_slowport_lock);
  45 static unsigned long ixp2000_slowport_irq_flags;
  46
  47 /*************************************************************************
  48  * Slowport access routines
  49  *************************************************************************/
  50 void ixp2000_acquire_slowport(struct slowport_cfg *new_cfg, struct slowport_cfg *old_cfg)
  51 {
  52         spin_lock_irqsave(&ixp2000_slowport_lock, ixp2000_slowport_irq_flags);
  53
  54         old_cfg->CCR = *IXP2000_SLOWPORT_CCR;
  55         old_cfg->WTC = *IXP2000_SLOWPORT_WTC2;
  56         old_cfg->RTC = *IXP2000_SLOWPORT_RTC2;
  57         old_cfg->PCR = *IXP2000_SLOWPORT_PCR;
  58         old_cfg->ADC = *IXP2000_SLOWPORT_ADC;
  59
  60         ixp2000_reg_write(IXP2000_SLOWPORT_CCR, new_cfg->CCR);
  61         ixp2000_reg_write(IXP2000_SLOWPORT_WTC2, new_cfg->WTC);
  62         ixp2000_reg_write(IXP2000_SLOWPORT_RTC2, new_cfg->RTC);
  63         ixp2000_reg_write(IXP2000_SLOWPORT_PCR, new_cfg->PCR);
  64         ixp2000_reg_wrb(IXP2000_SLOWPORT_ADC, new_cfg->ADC);
  65 }
  66
  67 void ixp2000_release_slowport(struct slowport_cfg *old_cfg)
  68 {
  69         ixp2000_reg_write(IXP2000_SLOWPORT_CCR, old_cfg->CCR);
  70         ixp2000_reg_write(IXP2000_SLOWPORT_WTC2, old_cfg->WTC);
  71         ixp2000_reg_write(IXP2000_SLOWPORT_RTC2, old_cfg->RTC);
  72         ixp2000_reg_write(IXP2000_SLOWPORT_PCR, old_cfg->PCR);
  73         ixp2000_reg_wrb(IXP2000_SLOWPORT_ADC, old_cfg->ADC);
  74
  75         spin_unlock_irqrestore(&ixp2000_slowport_lock,
  76                                         ixp2000_slowport_irq_flags);
  77 }
  78
  79 /*************************************************************************
  80  * Chip specific mappings shared by all IXP2000 systems
  81  *************************************************************************/
  82 static struct map_desc ixp2000_io_desc[] __initdata = {
  83         {
  84                 .virtual        = IXP2000_CAP_VIRT_BASE,
  85                 .pfn            = __phys_to_pfn(IXP2000_CAP_PHYS_BASE),
  86                 .length         = IXP2000_CAP_SIZE,
  87                 .type           = MT_DEVICE,
  88         }, {
  89                 .virtual        = IXP2000_INTCTL_VIRT_BASE,
  90                 .pfn            = __phys_to_pfn(IXP2000_INTCTL_PHYS_BASE),
  91                 .length         = IXP2000_INTCTL_SIZE,
  92                 .type           = MT_DEVICE,
  93         }, {
  94                 .virtual        = IXP2000_PCI_CREG_VIRT_BASE,
  95                 .pfn            = __phys_to_pfn(IXP2000_PCI_CREG_PHYS_BASE),
  96                 .length         = IXP2000_PCI_CREG_SIZE,
  97                 .type           = MT_DEVICE,
  98         }, {
  99                 .virtual        = IXP2000_PCI_CSR_VIRT_BASE,
 100                 .pfn            = __phys_to_pfn(IXP2000_PCI_CSR_PHYS_BASE),
 101                 .length         = IXP2000_PCI_CSR_SIZE,
 102                 .type           = MT_DEVICE,
 103         }, {
 104                 .virtual        = IXP2000_MSF_VIRT_BASE,
 105                 .pfn            = __phys_to_pfn(IXP2000_MSF_PHYS_BASE),
 106                 .length         = IXP2000_MSF_SIZE,
 107                 .type           = MT_DEVICE,
 108         }, {
 109                 .virtual        = IXP2000_SCRATCH_RING_VIRT_BASE,
 110                 .pfn            = __phys_to_pfn(IXP2000_SCRATCH_RING_PHYS_BASE),
 111                 .length         = IXP2000_SCRATCH_RING_SIZE,
 112                 .type           = MT_DEVICE,
 113         }, {
 114                 .virtual        = IXP2000_SRAM0_VIRT_BASE,
 115                 .pfn            = __phys_to_pfn(IXP2000_SRAM0_PHYS_BASE),
 116                 .length         = IXP2000_SRAM0_SIZE,
 117                 .type           = MT_DEVICE,
 118         }, {
 119                 .virtual        = IXP2000_PCI_IO_VIRT_BASE,
 120                 .pfn            = __phys_to_pfn(IXP2000_PCI_IO_PHYS_BASE),
 121                 .length         = IXP2000_PCI_IO_SIZE,
 122                 .type           = MT_DEVICE,
 123         }, {
 124                 .virtual        = IXP2000_PCI_CFG0_VIRT_BASE,
 125                 .pfn            = __phys_to_pfn(IXP2000_PCI_CFG0_PHYS_BASE),
 126                 .length         = IXP2000_PCI_CFG0_SIZE,
 127                 .type           = MT_DEVICE,
 128         }, {
 129                 .virtual        = IXP2000_PCI_CFG1_VIRT_BASE,
 130                 .pfn            = __phys_to_pfn(IXP2000_PCI_CFG1_PHYS_BASE),
 131                 .length         = IXP2000_PCI_CFG1_SIZE,
 132                 .type           = MT_DEVICE,
 133         }
 134 };
 135
 136 void __init ixp2000_map_io(void)
 137 {
 138         iotable_init(ixp2000_io_desc, ARRAY_SIZE(ixp2000_io_desc));
 139
 140         /* Set slowport to 8-bit mode.  */
 141         ixp2000_reg_wrb(IXP2000_SLOWPORT_FRM, 1);
 142 }
 143
 144
 145 /*************************************************************************
 146  * Serial port support for IXP2000
 147  *************************************************************************/
 148 static struct plat_serial8250_port ixp2000_serial_port[] = {
 149         {
 150                 .mapbase        = IXP2000_UART_PHYS_BASE,
 151                 .membase        = (char *)(IXP2000_UART_VIRT_BASE + 3),
 152                 .irq            = IRQ_IXP2000_UART,
 153                 .flags          = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,
 154                 .iotype         = UPIO_MEM,
 155                 .regshift       = 2,
 156                 .uartclk        = 50000000,
 157         },
 158         { },
 159 };
 160
 161 static struct resource ixp2000_uart_resource = {
 162         .start          = IXP2000_UART_PHYS_BASE,
 163         .end            = IXP2000_UART_PHYS_BASE + 0x1f,
 164         .flags          = IORESOURCE_MEM,
 165 };
 166
 167 static struct platform_device ixp2000_serial_device = {
 168         .name           = "serial8250",
 169         .id             = PLAT8250_DEV_PLATFORM,
 170         .dev            = {
 171                 .platform_data          = ixp2000_serial_port,
 172         },
 173         .num_resources  = 1,
 174         .resource       = &ixp2000_uart_resource,
 175 };
 176
 177 void __init ixp2000_uart_init(void)
 178 {
 179         platform_device_register(&ixp2000_serial_device);
 180 }
 181
 182
 183 /*************************************************************************
 184  * Timer-tick functions for IXP2000
 185  *************************************************************************/
 186 static unsigned ticks_per_jiffy;
 187 static unsigned ticks_per_usec;
 188 static unsigned next_jiffy_time;
 189 static volatile unsigned long *missing_jiffy_timer_csr;
 190
 191 unsigned long ixp2000_gettimeoffset (void)
 192 {
 193         unsigned long offset;
 194
 195         offset = next_jiffy_time - *missing_jiffy_timer_csr;
 196
 197         return offset / ticks_per_usec;
 198 }
 199
 200 static irqreturn_t ixp2000_timer_interrupt(int irq, void *dev_id)
 201 {
 202         /* clear timer 1 */
 203         ixp2000_reg_wrb(IXP2000_T1_CLR, 1);
 204
 205         while ((signed long)(next_jiffy_time - *missing_jiffy_timer_csr)
 206                                                         >= ticks_per_jiffy) {
 207                 timer_tick();
 208                 next_jiffy_time -= ticks_per_jiffy;
 209         }
 210
 211         return IRQ_HANDLED;
 212 }
 213
 214 static struct irqaction ixp2000_timer_irq = {
 215         .name           = "IXP2000 Timer Tick",
 216         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 217         .handler        = ixp2000_timer_interrupt,
 218 };
 219
 220 void __init ixp2000_init_time(unsigned long tick_rate)
 221 {
 222         ticks_per_jiffy = (tick_rate + HZ/2) / HZ;
 223         ticks_per_usec = tick_rate / 1000000;
 224
 225         /*
 226          * We use timer 1 as our timer interrupt.
 227          */
 228         ixp2000_reg_write(IXP2000_T1_CLR, 0);
 229         ixp2000_reg_write(IXP2000_T1_CLD, ticks_per_jiffy - 1);
 230         ixp2000_reg_write(IXP2000_T1_CTL, (1 << 7));
 231
 232         /*
 233          * We use a second timer as a monotonic counter for tracking
 234          * missed jiffies.  The IXP2000 has four timers, but if we're
 235          * on an A-step IXP2800, timer 2 and 3 don't work, so on those
 236          * chips we use timer 4.  Timer 4 is the only timer that can
 237          * be used for the watchdog, so we use timer 2 if we're on a
 238          * non-buggy chip.
 239          */
 240         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
 241                 printk(KERN_INFO "Enabling IXP2800 erratum #25 workaround\n");
 242
 243                 ixp2000_reg_write(IXP2000_T4_CLR, 0);
 244                 ixp2000_reg_write(IXP2000_T4_CLD, -1);
 245                 ixp2000_reg_wrb(IXP2000_T4_CTL, (1 << 7));
 246                 missing_jiffy_timer_csr = IXP2000_T4_CSR;
 247         } else {
 248                 ixp2000_reg_write(IXP2000_T2_CLR, 0);
 249                 ixp2000_reg_write(IXP2000_T2_CLD, -1);
 250                 ixp2000_reg_wrb(IXP2000_T2_CTL, (1 << 7));
 251                 missing_jiffy_timer_csr = IXP2000_T2_CSR;
 252         }
 253         next_jiffy_time = 0xffffffff;
 254
 255         /* register for interrupt */
 256         setup_irq(IRQ_IXP2000_TIMER1, &ixp2000_timer_irq);
 257 }
 258
 259 /*************************************************************************
 260  * GPIO helpers
 261  *************************************************************************/
 262 static unsigned long GPIO_IRQ_falling_edge;
 263 static unsigned long GPIO_IRQ_rising_edge;
 264 static unsigned long GPIO_IRQ_level_low;
 265 static unsigned long GPIO_IRQ_level_high;
 266
 267 static void update_gpio_int_csrs(void)
 268 {
 269         ixp2000_reg_write(IXP2000_GPIO_FEDR, GPIO_IRQ_falling_edge);
 270         ixp2000_reg_write(IXP2000_GPIO_REDR, GPIO_IRQ_rising_edge);
 271         ixp2000_reg_write(IXP2000_GPIO_LSLR, GPIO_IRQ_level_low);
 272         ixp2000_reg_wrb(IXP2000_GPIO_LSHR, GPIO_IRQ_level_high);
 273 }
 274
 275 void gpio_line_config(int line, int direction)
 276 {
 277         unsigned long flags;
 278
 279         local_irq_save(flags);
 280         if (direction == GPIO_OUT) {
 281                 /* if it's an output, it ain't an interrupt anymore */
 282                 GPIO_IRQ_falling_edge &= ~(1 << line);
 283                 GPIO_IRQ_rising_edge &= ~(1 << line);
 284                 GPIO_IRQ_level_low &= ~(1 << line);
 285                 GPIO_IRQ_level_high &= ~(1 << line);
 286                 update_gpio_int_csrs();
 287
 288                 ixp2000_reg_wrb(IXP2000_GPIO_PDSR, 1 << line);
 289         } else if (direction == GPIO_IN) {
 290                 ixp2000_reg_wrb(IXP2000_GPIO_PDCR, 1 << line);
 291         }
 292         local_irq_restore(flags);
 293 }
 294 EXPORT_SYMBOL(gpio_line_config);
 295
 296
 297 /*************************************************************************
 298  * IRQ handling IXP2000
 299  *************************************************************************/
 300 static void ixp2000_GPIO_irq_handler(unsigned int irq, struct irq_desc *desc)
 301 {
 302         int i;
 303         unsigned long status = *IXP2000_GPIO_INST;
 304
 305         for (i = 0; i <= 7; i++) {
 306                 if (status & (1<<i)) {
 307                         generic_handle_irq(i + IRQ_IXP2000_GPIO0);
 308                 }
 309         }
 310 }
 311
 312 static int ixp2000_GPIO_irq_type(struct irq_data *d, unsigned int type)
 313 {
 314         int line = d->irq - IRQ_IXP2000_GPIO0;
 315
 316         /*
 317          * First, configure this GPIO line as an input.
 318          */
 319         ixp2000_reg_write(IXP2000_GPIO_PDCR, 1 << line);
 320
 321         /*
 322          * Then, set the proper trigger type.
 323          */
 324         if (type & IRQ_TYPE_EDGE_FALLING)
 325                 GPIO_IRQ_falling_edge |= 1 << line;
 326         else
 327                 GPIO_IRQ_falling_edge &= ~(1 << line);
 328         if (type & IRQ_TYPE_EDGE_RISING)
 329                 GPIO_IRQ_rising_edge |= 1 << line;
 330         else
 331                 GPIO_IRQ_rising_edge &= ~(1 << line);
 332         if (type & IRQ_TYPE_LEVEL_LOW)
 333                 GPIO_IRQ_level_low |= 1 << line;
 334         else
 335                 GPIO_IRQ_level_low &= ~(1 << line);
 336         if (type & IRQ_TYPE_LEVEL_HIGH)
 337                 GPIO_IRQ_level_high |= 1 << line;
 338         else
 339                 GPIO_IRQ_level_high &= ~(1 << line);
 340         update_gpio_int_csrs();
 341
 342         return 0;
 343 }
 344
 345 static void ixp2000_GPIO_irq_mask_ack(struct irq_data *d)
 346 {
 347         unsigned int irq = d->irq;
 348
 349         ixp2000_reg_write(IXP2000_GPIO_INCR, (1 << (irq - IRQ_IXP2000_GPIO0)));
 350
 351         ixp2000_reg_write(IXP2000_GPIO_EDSR, (1 << (irq - IRQ_IXP2000_GPIO0)));
 352         ixp2000_reg_write(IXP2000_GPIO_LDSR, (1 << (irq - IRQ_IXP2000_GPIO0)));
 353         ixp2000_reg_wrb(IXP2000_GPIO_INST, (1 << (irq - IRQ_IXP2000_GPIO0)));
 354 }
 355
 356 static void ixp2000_GPIO_irq_mask(struct irq_data *d)
 357 {
 358         unsigned int irq = d->irq;
 359
 360         ixp2000_reg_wrb(IXP2000_GPIO_INCR, (1 << (irq - IRQ_IXP2000_GPIO0)));
 361 }
 362
 363 static void ixp2000_GPIO_irq_unmask(struct irq_data *d)
 364 {
 365         unsigned int irq = d->irq;
 366
 367         ixp2000_reg_write(IXP2000_GPIO_INSR, (1 << (irq - IRQ_IXP2000_GPIO0)));
 368 }
 369
 370 static struct irq_chip ixp2000_GPIO_irq_chip = {
 371         .irq_ack        = ixp2000_GPIO_irq_mask_ack,
 372         .irq_mask       = ixp2000_GPIO_irq_mask,
 373         .irq_unmask     = ixp2000_GPIO_irq_unmask,
 374         .irq_set_type   = ixp2000_GPIO_irq_type,
 375 };
 376
 377 static void ixp2000_pci_irq_mask(struct irq_data *d)
 378 {
 379         unsigned long temp = *IXP2000_PCI_XSCALE_INT_ENABLE;
 380         if (d->irq == IRQ_IXP2000_PCIA)
 381                 ixp2000_reg_wrb(IXP2000_PCI_XSCALE_INT_ENABLE, (temp & ~(1 << 26)));
 382         else if (d->irq == IRQ_IXP2000_PCIB)
 383                 ixp2000_reg_wrb(IXP2000_PCI_XSCALE_INT_ENABLE, (temp & ~(1 << 27)));
 384 }
 385
 386 static void ixp2000_pci_irq_unmask(struct irq_data *d)
 387 {
 388         unsigned long temp = *IXP2000_PCI_XSCALE_INT_ENABLE;
 389         if (d->irq == IRQ_IXP2000_PCIA)
 390                 ixp2000_reg_write(IXP2000_PCI_XSCALE_INT_ENABLE, (temp | (1 << 26)));
 391         else if (d->irq == IRQ_IXP2000_PCIB)
 392                 ixp2000_reg_write(IXP2000_PCI_XSCALE_INT_ENABLE, (temp | (1 << 27)));
 393 }
 394
 395 /*
 396  * Error interrupts. These are used extensively by the microengine drivers
 397  */
 398 static void ixp2000_err_irq_handler(unsigned int irq, struct irq_desc *desc)
 399 {
 400         int i;
 401         unsigned long status = *IXP2000_IRQ_ERR_STATUS;
 402
 403         for(i = 31; i >= 0; i--) {
 404                 if(status & (1 << i)) {
 405                         generic_handle_irq(IRQ_IXP2000_DRAM0_MIN_ERR + i);
 406                 }
 407         }
 408 }
 409
 410 static void ixp2000_err_irq_mask(struct irq_data *d)
 411 {
 412         ixp2000_reg_write(IXP2000_IRQ_ERR_ENABLE_CLR,
 413                         (1 << (d->irq - IRQ_IXP2000_DRAM0_MIN_ERR)));
 414 }
 415
 416 static void ixp2000_err_irq_unmask(struct irq_data *d)
 417 {
 418         ixp2000_reg_write(IXP2000_IRQ_ERR_ENABLE_SET,
 419                         (1 << (d->irq - IRQ_IXP2000_DRAM0_MIN_ERR)));
 420 }
 421
 422 static struct irq_chip ixp2000_err_irq_chip = {
 423         .irq_ack        = ixp2000_err_irq_mask,
 424         .irq_mask       = ixp2000_err_irq_mask,
 425         .irq_unmask     = ixp2000_err_irq_unmask
 426 };
 427
 428 static struct irq_chip ixp2000_pci_irq_chip = {
 429         .irq_ack        = ixp2000_pci_irq_mask,
 430         .irq_mask       = ixp2000_pci_irq_mask,
 431         .irq_unmask     = ixp2000_pci_irq_unmask
 432 };
 433
 434 static void ixp2000_irq_mask(struct irq_data *d)
 435 {
 436         ixp2000_reg_wrb(IXP2000_IRQ_ENABLE_CLR, (1 << d->irq));
 437 }
 438
 439 static void ixp2000_irq_unmask(struct irq_data *d)
 440 {
 441         ixp2000_reg_write(IXP2000_IRQ_ENABLE_SET, (1 << d->irq));
 442 }
 443
 444 static struct irq_chip ixp2000_irq_chip = {
 445         .irq_ack        = ixp2000_irq_mask,
 446         .irq_mask       = ixp2000_irq_mask,
 447         .irq_unmask     = ixp2000_irq_unmask
 448 };
 449
 450 void __init ixp2000_init_irq(void)
 451 {
 452         int irq;
 453
 454         /*
 455          * Mask all sources
 456          */
 457         ixp2000_reg_write(IXP2000_IRQ_ENABLE_CLR, 0xffffffff);
 458         ixp2000_reg_write(IXP2000_FIQ_ENABLE_CLR, 0xffffffff);
 459
 460         /* clear all GPIO edge/level detects */
 461         ixp2000_reg_write(IXP2000_GPIO_REDR, 0);
 462         ixp2000_reg_write(IXP2000_GPIO_FEDR, 0);
 463         ixp2000_reg_write(IXP2000_GPIO_LSHR, 0);
 464         ixp2000_reg_write(IXP2000_GPIO_LSLR, 0);
 465         ixp2000_reg_write(IXP2000_GPIO_INCR, -1);
 466
 467         /* clear PCI interrupt sources */
 468         ixp2000_reg_wrb(IXP2000_PCI_XSCALE_INT_ENABLE, 0);
 469
 470         /*
 471          * Certain bits in the IRQ status register of the
 472          * IXP2000 are reserved. Instead of trying to map
 473          * things non 1:1 from bit position to IRQ number,
 474          * we mark the reserved IRQs as invalid. This makes
 475          * our mask/unmask code much simpler.
 476          */
 477         for (irq = IRQ_IXP2000_SOFT_INT; irq <= IRQ_IXP2000_THDB3; irq++) {
 478                 if ((1 << irq) & IXP2000_VALID_IRQ_MASK) {
 479                         irq_set_chip_and_handler(irq, &ixp2000_irq_chip,
 480                                                  handle_level_irq);
 481                         set_irq_flags(irq, IRQF_VALID);
 482                 } else set_irq_flags(irq, 0);
 483         }
 484
 485         for (irq = IRQ_IXP2000_DRAM0_MIN_ERR; irq <= IRQ_IXP2000_SP_INT; irq++) {
 486                 if((1 << (irq - IRQ_IXP2000_DRAM0_MIN_ERR)) &
 487                                 IXP2000_VALID_ERR_IRQ_MASK) {
 488                         irq_set_chip_and_handler(irq, &ixp2000_err_irq_chip,
 489                                                  handle_level_irq);
 490                         set_irq_flags(irq, IRQF_VALID);
 491                 }
 492                 else
 493                         set_irq_flags(irq, 0);
 494         }
 495         irq_set_chained_handler(IRQ_IXP2000_ERRSUM, ixp2000_err_irq_handler);
 496
 497         for (irq = IRQ_IXP2000_GPIO0; irq <= IRQ_IXP2000_GPIO7; irq++) {
 498                 irq_set_chip_and_handler(irq, &ixp2000_GPIO_irq_chip,
 499                                          handle_level_irq);
 500                 set_irq_flags(irq, IRQF_VALID);
 501         }
 502         irq_set_chained_handler(IRQ_IXP2000_GPIO, ixp2000_GPIO_irq_handler);
 503
 504         /*
 505          * Enable PCI irqs.  The actual PCI[AB] decoding is done in
 506          * entry-macro.S, so we don't need a chained handler for the
 507          * PCI interrupt source.
 508          */
 509         ixp2000_reg_write(IXP2000_IRQ_ENABLE_SET, (1 << IRQ_IXP2000_PCI));
 510         for (irq = IRQ_IXP2000_PCIA; irq <= IRQ_IXP2000_PCIB; irq++) {
 511                 irq_set_chip_and_handler(irq, &ixp2000_pci_irq_chip,
 512                                          handle_level_irq);
 513                 set_irq_flags(irq, IRQF_VALID);
 514         }
 515 }
 516