text: /*
   * atmel_df_pow2.c - convert Atmel Dataflashes to Power of 2 mode
   *
   * Copyright 2009 Analog Devices Inc.
   *
   * Licensed under the 2-clause BSD.
   */
  
  #include <common.h>
  #include <exports.h>
  #include <spi.h>
  
  #define CMD_ID    0x9f
  #define CMD_STAT  0xd7
  #define CMD_CFG   0x3d
  
  static int flash_cmd(struct spi_slave *slave, uchar cmd, uchar *buf, int len)
  {
  	buf[0] = cmd;
  	return spi_xfer(slave, 8 * len, buf, buf, SPI_XFER_BEGIN | SPI_XFER_END);
  }
  
  static int flash_status(struct spi_slave *slave)
  {
  	uchar buf[2];
  	if (flash_cmd(slave, CMD_STAT, buf, sizeof(buf)))
  		return -1;
  	return buf[1];
  }
  
  static int flash_set_pow2(struct spi_slave *slave)
  {
  	int ret;
  	uchar buf[4];
  
  	buf[1] = 0x2a;
  	buf[2] = 0x80;
  	buf[3] = 0xa6;
  
  	ret = flash_cmd(slave, CMD_CFG, buf, sizeof(buf));
  	if (ret)
  		return ret;
  
  	/* wait Tp, or 6 msec */
  	udelay(6000);
  
  	ret = flash_status(slave);
  	if (ret == -1)
  		return 1;
  
  	return ret & 0x1 ? 0 : 1;
  }
  
  static int flash_check(struct spi_slave *slave)
  {
  	int ret;
  	uchar buf[4];
  
  	ret = flash_cmd(slave, CMD_ID, buf, sizeof(buf));
  	if (ret)
  		return ret;
  
  	if (buf[1] != 0x1F) {
  		printf("atmel flash not found (id[0] = %#x)\n", buf[1]);
  		return 1;
  	}
  
  	if ((buf[2] >> 5) != 0x1) {
  		printf("AT45 flash not found (id[0] = %#x)\n", buf[2]);
  		return 2;
  	}
  
  	return 0;
  }
  
  static char *getline(void)
  {
  	static char buffer[100];
  	char c;
  	size_t i;
  
  	i = 0;
  	while (1) {
  		buffer[i] = '\0';
  
  		c = getc();
  
  		switch (c) {
  		case '\r':	/* Enter/Return key */
  		case '\n':
  			puts("\n");
  			return buffer;
  
  		case 0x03:	/* ^C - break */
  			return NULL;
  
  		case 0x5F:
  		case 0x08:	/* ^H  - backspace */
  		case 0x7F:	/* DEL - backspace */
  			if (i) {
  				puts("\b \b");
  				i--;
  			}
  			break;
  
  		default:
  			/* Ignore control characters */
  			if (c < 0x20)
  				break;
  			/* Queue up all other characters */
  			buffer[i++] = c;
  			printf("%c", c);
  			break;
  		}
  	}
  }
  
  int atmel_df_pow2(int argc, char * const argv[])
  {
  	/* Print the ABI version */
  	app_startup(argv);
  	if (XF_VERSION != get_version()) {
  		printf("Expects ABI version %d\n", XF_VERSION);
  		printf("Actual U-Boot ABI version %lu\n", get_version());
  		printf("Can't run\n\n");
  		return 1;
  	}
  
  	while (1) {
  		struct spi_slave *slave;
  		char *line, *p;
  		int bus, cs, status;
  
  		puts("\nenter the [BUS:]CS of the SPI flash: ");
  		line = getline();
  
  		/* CTRL+C */
  		if (!line)
  			return 0;
  		if (line[0] == '\0')
  			continue;
  
  		bus = cs = simple_strtoul(line, &p, 10);
  		if (*p) {
  			if (*p == ':') {
  				++p;
  				cs = simple_strtoul(p, &p, 10);
  			}
  			if (*p) {
  				puts("invalid format, please try again\n");
  				continue;
  			}
  		} else
  			bus = 0;
  
  		printf("\ngoing to work with dataflash at %i:%i\n", bus, cs);
  
  		/* use a low speed -- it'll work with all devices, and
  		 * speed here doesn't really matter.
  		 */
  		slave = spi_setup_slave(bus, cs, 1000, SPI_MODE_3);
  		if (!slave) {
  			puts("unable to setup slave\n");
  			continue;
  		}
  
  		if (spi_claim_bus(slave)) {
  			spi_free_slave(slave);
  			continue;
  		}
  
  		if (flash_check(slave)) {
  			puts("no flash found\n");
  			goto done;
  		}
  
  		status = flash_status(slave);
  		if (status == -1) {
  			puts("unable to read status register\n");
  			goto done;
  		}
  		if (status & 0x1) {
  			puts("flash is already in power-of-2 mode!\n");
  			goto done;
  		}
  
  		puts("are you sure you wish to set power-of-2 mode?\n");
  		puts("this operation is permanent and irreversible\n");
  		printf("enter YES to continue: ");
  		line = getline();
  		if (!line || strcmp(line, "YES"))
  			goto done;
  
  		if (flash_set_pow2(slave)) {
  			puts("setting pow2 mode failed\n");
  			goto done;
  		}
  
  		puts(
  			"Configuration should be updated now.  You will have to\n"
  			"power cycle the part in order to finish the conversion.\n"
  		);
  
   done:
  		spi_release_bus(slave);
  		spi_free_slave(slave);
  	}
  }
  