e1000: Allow direct access to the E1000 SPI EEPROM device

As a part of the manufacturing process for some of our custom hardware,
we are programming the EEPROMs attached to our Intel 82571EB controllers
from software using U-Boot and Linux.

This code provides several conditionally-compiled features to assist in
our manufacturing process:

  CONFIG_CMD_E1000:
    This is a basic "e1000" command which allows querying the controller
    and (if other config options are set) performing EEPROM programming.
    In particular, with CONFIG_E1000_SPI this allows you to display a
    hex-dump of the EEPROM, copy to/from main memory, and verify/update
    the software checksum.

  CONFIG_E1000_SPI_GENERIC:
    Build a generic SPI driver providing the standard U-Boot SPI driver
    interface.  This allows commands such as "sspi" to access the bus
    attached to the E1000 controller.  Additionally, some E1000 chipsets
    can support user data in a reserved space in the E1000 EEPROM which
    could be used for U-Boot environment storage.

  CONFIG_E1000_SPI:
    The core SPI access code used by the above interfaces.

For example, the following commands allow you to program the EEPROM from
a USB device (assumes CONFIG_E1000_SPI and CONFIG_CMD_E1000 are enabled):
  usb start
  fatload usb 0 $loadaddr 82571EB_No_Mgmt_Discrete-LOM.bin
  e1000 0 spi program $loadaddr 0 1024
  e1000 0 spi checksum update

Please keep in mind that the Intel-provided .eep files are organized as
16-bit words.  When converting them to binary form for programming you
must byteswap each 16-bit word so that it is in little-endian form.

This means that when reading and writing words to the SPI EEPROM, the
bit ordering for each word looks like this on the wire:

  Time >>>
------------------------------------------------------------------
  ... [7, 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, 8], ...
------------------------------------------------------------------
  (MSB is 15, LSB is 0).

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Cc: Ben Warren <biggerbadderben@gmail.com>

4 files changed, 657 insertions, 1 deletions

diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 24eb361acf..15eee8d8c4 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -37,6 +37,7 @@ COBJS-$(CONFIG_DESIGNWARE_ETH) += designware.o
 COBJS-$(CONFIG_DRIVER_DM9000) += dm9000x.o
 COBJS-$(CONFIG_DNET) += dnet.o
 COBJS-$(CONFIG_E1000) += e1000.o
+COBJS-$(CONFIG_E1000_SPI) += e1000_spi.o
 COBJS-$(CONFIG_EEPRO100) += eepro100.o
 COBJS-$(CONFIG_ENC28J60) += enc28j60.o
 COBJS-$(CONFIG_EP93XX) += ep93xx_eth.o
diff --git a/drivers/net/e1000.c b/drivers/net/e1000.c
index 7a6ecab452..c86bf0a0e7 100644
--- a/drivers/net/e1000.c
+++ b/drivers/net/e1000.c
@@ -5155,6 +5155,9 @@ void e1000_get_bus_type(struct e1000_hw *hw)
 	}
 }
 
+/* A list of all registered e1000 devices */
+static LIST_HEAD(e1000_hw_list);
+
 /**************************************************************************
 PROBE - Look for an adapter, this routine's visible to the outside
 You should omit the last argument struct pci_device * for a non-PCI NIC
@@ -5234,8 +5237,9 @@ e1000_initialize(bd_t * bis)
 		if (e1000_check_phy_reset_block(hw))
 			E1000_ERR(nic, "PHY Reset is blocked!\n");
 
-		/* Basic init was OK, reset the hardware */
+		/* Basic init was OK, reset the hardware and allow SPI access */
 		e1000_reset_hw(hw);
+		list_add_tail(&hw->list_node, &e1000_hw_list);
 
 		/* Validate the EEPROM and get chipset information */
 #if !(defined(CONFIG_AP1000) || defined(CONFIG_MVBC_1G))
@@ -5263,3 +5267,63 @@ e1000_initialize(bd_t * bis)
 
 	return i;
 }
+
+struct e1000_hw *e1000_find_card(unsigned int cardnum)
+{
+	struct e1000_hw *hw;
+
+	list_for_each_entry(hw, &e1000_hw_list, list_node)
+		if (hw->cardnum == cardnum)
+			return hw;
+
+	return NULL;
+}
+
+#ifdef CONFIG_CMD_E1000
+static int do_e1000(cmd_tbl_t *cmdtp, int flag,
+		int argc, char * const argv[])
+{
+	struct e1000_hw *hw;
+
+	if (argc < 3) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* Make sure we can find the requested e1000 card */
+	hw = e1000_find_card(simple_strtoul(argv[1], NULL, 10));
+	if (!hw) {
+		printf("e1000: ERROR: No such device: e1000#%s\n", argv[1]);
+		return 1;
+	}
+
+	if (!strcmp(argv[2], "print-mac-address")) {
+		unsigned char *mac = hw->nic->enetaddr;
+		printf("%02x:%02x:%02x:%02x:%02x:%02x\n",
+			mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+		return 0;
+	}
+
+#ifdef CONFIG_E1000_SPI
+	/* Handle the "SPI" subcommand */
+	if (!strcmp(argv[2], "spi"))
+		return do_e1000_spi(cmdtp, hw, argc - 3, argv + 3);
+#endif
+
+	cmd_usage(cmdtp);
+	return 1;
+}
+
+U_BOOT_CMD(
+	e1000, 7, 0, do_e1000,
+	"Intel e1000 controller management",
+	/*  */"<card#> print-mac-address\n"
+#ifdef CONFIG_E1000_SPI
+	"e1000 <card#> spi show [<offset> [<length>]]\n"
+	"e1000 <card#> spi dump <addr> <offset> <length>\n"
+	"e1000 <card#> spi program <addr> <offset> <length>\n"
+	"e1000 <card#> spi checksum [update]\n"
+#endif
+	"       - Manage the Intel E1000 PCI device"
+);
+#endif /* not CONFIG_CMD_E1000 */
diff --git a/drivers/net/e1000.h b/drivers/net/e1000.h
index fc5ed57f93..05f2bcea29 100644
--- a/drivers/net/e1000.h
+++ b/drivers/net/e1000.h
@@ -35,12 +35,17 @@
 #define _E1000_HW_H_
 
 #include <common.h>
+#include <linux/list.h>
 #include <malloc.h>
 #include <net.h>
 #include <netdev.h>
 #include <asm/io.h>
 #include <pci.h>
 
+#ifdef CONFIG_E1000_SPI
+#include <spi.h>
+#endif
+
 #define E1000_ERR(NIC, fmt, args...) \
 	printf("e1000: %s: ERROR: " fmt, (NIC)->name ,##args)
 
@@ -72,12 +77,18 @@ struct e1000_hw;
 struct e1000_hw_stats;
 
 /* Internal E1000 helper functions */
+struct e1000_hw *e1000_find_card(unsigned int cardnum);
 int32_t e1000_acquire_eeprom(struct e1000_hw *hw);
 void e1000_standby_eeprom(struct e1000_hw *hw);
 void e1000_release_eeprom(struct e1000_hw *hw);
 void e1000_raise_ee_clk(struct e1000_hw *hw, uint32_t *eecd);
 void e1000_lower_ee_clk(struct e1000_hw *hw, uint32_t *eecd);
 
+#ifdef CONFIG_E1000_SPI
+int do_e1000_spi(cmd_tbl_t *cmdtp, struct e1000_hw *hw,
+		int argc, char * const argv[]);
+#endif
+
 typedef enum {
 	FALSE = 0,
 	TRUE = 1
@@ -1068,7 +1079,11 @@ typedef enum {
 
 /* Structure containing variables used by the shared code (e1000_hw.c) */
 struct e1000_hw {
+	struct list_head list_node;
 	struct eth_device *nic;
+#ifdef CONFIG_E1000_SPI
+	struct spi_slave spi;
+#endif
 	unsigned int cardnum;
 
 	pci_dev_t pdev;
diff --git a/drivers/net/e1000_spi.c b/drivers/net/e1000_spi.c
new file mode 100644
index 0000000000..5491780193
--- /dev/null
+++ b/drivers/net/e1000_spi.c
@@ -0,0 +1,576 @@
+#include "e1000.h"
+
+/*-----------------------------------------------------------------------
+ * SPI transfer
+ *
+ * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
+ * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
+ *
+ * The source of the outgoing bits is the "dout" parameter and the
+ * destination of the input bits is the "din" parameter.  Note that "dout"
+ * and "din" can point to the same memory location, in which case the
+ * input data overwrites the output data (since both are buffered by
+ * temporary variables, this is OK).
+ *
+ * This may be interrupted with Ctrl-C if "intr" is true, otherwise it will
+ * never return an error.
+ */
+static int e1000_spi_xfer(struct e1000_hw *hw, unsigned int bitlen,
+		const void *dout_mem, void *din_mem, boolean_t intr)
+{
+	const uint8_t *dout = dout_mem;
+	uint8_t *din = din_mem;
+
+	uint8_t mask = 0;
+	uint32_t eecd;
+	unsigned long i;
+
+	/* Pre-read the control register */
+	eecd = E1000_READ_REG(hw, EECD);
+
+	/* Iterate over each bit */
+	for (i = 0, mask = 0x80; i < bitlen; i++, mask = (mask >> 1)?:0x80) {
+		/* Check for interrupt */
+		if (intr && ctrlc())
+			return -1;
+
+		/* Determine the output bit */
+		if (dout && dout[i >> 3] & mask)
+			eecd |=  E1000_EECD_DI;
+		else
+			eecd &= ~E1000_EECD_DI;
+
+		/* Write the output bit and wait 50us */
+		E1000_WRITE_REG(hw, EECD, eecd);
+		E1000_WRITE_FLUSH(hw);
+		udelay(50);
+
+		/* Poke the clock (waits 50us) */
+		e1000_raise_ee_clk(hw, &eecd);
+
+		/* Now read the input bit */
+		eecd = E1000_READ_REG(hw, EECD);
+		if (din) {
+			if (eecd & E1000_EECD_DO)
+				din[i >> 3] |=  mask;
+			else
+				din[i >> 3] &= ~mask;
+		}
+
+		/* Poke the clock again (waits 50us) */
+		e1000_lower_ee_clk(hw, &eecd);
+	}
+
+	/* Now clear any remaining bits of the input */
+	if (din && (i & 7))
+		din[i >> 3] &= ~((mask << 1) - 1);
+
+	return 0;
+}
+
+#ifdef CONFIG_E1000_SPI_GENERIC
+static inline struct e1000_hw *e1000_hw_from_spi(struct spi_slave *spi)
+{
+	return container_of(spi, struct e1000_hw, spi);
+}
+
+/* Not sure why all of these are necessary */
+void spi_init_r(void) { /* Nothing to do */ }
+void spi_init_f(void) { /* Nothing to do */ }
+void spi_init(void)   { /* Nothing to do */ }
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+		unsigned int max_hz, unsigned int mode)
+{
+	/* Find the right PCI device */
+	struct e1000_hw *hw = e1000_find_card(bus);
+	if (!hw) {
+		printf("ERROR: No such e1000 device: e1000#%u\n", bus);
+		return NULL;
+	}
+
+	/* Make sure it has an SPI chip */
+	if (hw->eeprom.type != e1000_eeprom_spi) {
+		E1000_ERR(hw->nic, "No attached SPI EEPROM found!\n");
+		return NULL;
+	}
+
+	/* Argument sanity checks */
+	if (cs != 0) {
+		E1000_ERR(hw->nic, "No such SPI chip: %u\n", cs);
+		return NULL;
+	}
+	if (mode != SPI_MODE_0) {
+		E1000_ERR(hw->nic, "Only SPI MODE-0 is supported!\n");
+		return NULL;
+	}
+
+	/* TODO: Use max_hz somehow */
+	E1000_DBG(hw->nic, "EEPROM SPI access requested\n");
+	return &hw->spi;
+}
+
+void spi_free_slave(struct spi_slave *spi)
+{
+	struct e1000_hw *hw = e1000_hw_from_spi(spi);
+	E1000_DBG(hw->nic, "EEPROM SPI access released\n");
+}
+
+int spi_claim_bus(struct spi_slave *spi)
+{
+	struct e1000_hw *hw = e1000_hw_from_spi(spi);
+
+	if (e1000_acquire_eeprom(hw)) {
+		E1000_ERR(hw->nic, "EEPROM SPI cannot be acquired!\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *spi)
+{
+	struct e1000_hw *hw = e1000_hw_from_spi(spi);
+	e1000_release_eeprom(hw);
+}
+
+/* Skinny wrapper around e1000_spi_xfer */
+int spi_xfer(struct spi_slave *spi, unsigned int bitlen,
+		const void *dout_mem, void *din_mem, unsigned long flags)
+{
+	struct e1000_hw *hw = e1000_hw_from_spi(spi);
+	int ret;
+
+	if (flags & SPI_XFER_BEGIN)
+		e1000_standby_eeprom(hw);
+
+	ret = e1000_spi_xfer(hw, bitlen, dout_mem, din_mem, TRUE);
+
+	if (flags & SPI_XFER_END)
+		e1000_standby_eeprom(hw);
+
+	return ret;
+}
+
+#endif /* not CONFIG_E1000_SPI_GENERIC */
+
+#ifdef CONFIG_CMD_E1000
+
+/* The EEPROM opcodes */
+#define SPI_EEPROM_ENABLE_WR	0x06
+#define SPI_EEPROM_DISABLE_WR	0x04
+#define SPI_EEPROM_WRITE_STATUS	0x01
+#define SPI_EEPROM_READ_STATUS	0x05
+#define SPI_EEPROM_WRITE_PAGE	0x02
+#define SPI_EEPROM_READ_PAGE	0x03
+
+/* The EEPROM status bits */
+#define SPI_EEPROM_STATUS_BUSY	0x01
+#define SPI_EEPROM_STATUS_WREN	0x02
+
+static int e1000_spi_eeprom_enable_wr(struct e1000_hw *hw, boolean_t intr)
+{
+	u8 op[] = { SPI_EEPROM_ENABLE_WR };
+	e1000_standby_eeprom(hw);
+	return e1000_spi_xfer(hw, 8*sizeof(op), op, NULL, intr);
+}
+
+/*
+ * These have been tested to perform correctly, but they are not used by any
+ * of the EEPROM commands at this time.
+ */
+#if 0
+static int e1000_spi_eeprom_disable_wr(struct e1000_hw *hw, boolean_t intr)
+{
+	u8 op[] = { SPI_EEPROM_DISABLE_WR };
+	e1000_standby_eeprom(hw);
+	return e1000_spi_xfer(hw, 8*sizeof(op), op, NULL, intr);
+}
+
+static int e1000_spi_eeprom_write_status(struct e1000_hw *hw,
+		u8 status, boolean_t intr)
+{
+	u8 op[] = { SPI_EEPROM_WRITE_STATUS, status };
+	e1000_standby_eeprom(hw);
+	return e1000_spi_xfer(hw, 8*sizeof(op), op, NULL, intr);
+}
+#endif
+
+static int e1000_spi_eeprom_read_status(struct e1000_hw *hw, boolean_t intr)
+{
+	u8 op[] = { SPI_EEPROM_READ_STATUS, 0 };
+	e1000_standby_eeprom(hw);
+	if (e1000_spi_xfer(hw, 8*sizeof(op), op, op, intr))
+		return -1;
+	return op[1];
+}
+
+static int e1000_spi_eeprom_write_page(struct e1000_hw *hw,
+		const void *data, u16 off, u16 len, boolean_t intr)
+{
+	u8 op[] = {
+		SPI_EEPROM_WRITE_PAGE,
+		(off >> (hw->eeprom.address_bits - 8)) & 0xff, off & 0xff
+	};
+
+	e1000_standby_eeprom(hw);
+
+	if (e1000_spi_xfer(hw, 8 + hw->eeprom.address_bits, op, NULL, intr))
+		return -1;
+	if (e1000_spi_xfer(hw, len << 3, data, NULL, intr))
+		return -1;
+
+	return 0;
+}
+
+static int e1000_spi_eeprom_read_page(struct e1000_hw *hw,
+		void *data, u16 off, u16 len, boolean_t intr)
+{
+	u8 op[] = {
+		SPI_EEPROM_READ_PAGE,
+		(off >> (hw->eeprom.address_bits - 8)) & 0xff, off & 0xff
+	};
+
+	e1000_standby_eeprom(hw);
+
+	if (e1000_spi_xfer(hw, 8 + hw->eeprom.address_bits, op, NULL, intr))
+		return -1;
+	if (e1000_spi_xfer(hw, len << 3, NULL, data, intr))
+		return -1;
+
+	return 0;
+}
+
+static int e1000_spi_eeprom_poll_ready(struct e1000_hw *hw, boolean_t intr)
+{
+	int status;
+	while ((status = e1000_spi_eeprom_read_status(hw, intr)) >= 0) {
+		if (!(status & SPI_EEPROM_STATUS_BUSY))
+			return 0;
+	}
+	return -1;
+}
+
+static int e1000_spi_eeprom_dump(struct e1000_hw *hw,
+		void *data, u16 off, unsigned int len, boolean_t intr)
+{
+	/* Interruptibly wait for the EEPROM to be ready */
+	if (e1000_spi_eeprom_poll_ready(hw, intr))
+		return -1;
+
+	/* Dump each page in sequence */
+	while (len) {
+		/* Calculate the data bytes on this page */
+		u16 pg_off = off & (hw->eeprom.page_size - 1);
+		u16 pg_len = hw->eeprom.page_size - pg_off;
+		if (pg_len > len)
+			pg_len = len;
+
+		/* Now dump the page */
+		if (e1000_spi_eeprom_read_page(hw, data, off, pg_len, intr))
+			return -1;
+
+		/* Otherwise go on to the next page */
+		len  -= pg_len;
+		off  += pg_len;
+		data += pg_len;
+	}
+
+	/* We're done! */
+	return 0;
+}
+
+static int e1000_spi_eeprom_program(struct e1000_hw *hw,
+		const void *data, u16 off, u16 len, boolean_t intr)
+{
+	/* Program each page in sequence */
+	while (len) {
+		/* Calculate the data bytes on this page */
+		u16 pg_off = off & (hw->eeprom.page_size - 1);
+		u16 pg_len = hw->eeprom.page_size - pg_off;
+		if (pg_len > len)
+			pg_len = len;
+
+		/* Interruptibly wait for the EEPROM to be ready */
+		if (e1000_spi_eeprom_poll_ready(hw, intr))
+			return -1;
+
+		/* Enable write access */
+		if (e1000_spi_eeprom_enable_wr(hw, intr))
+			return -1;
+
+		/* Now program the page */
+		if (e1000_spi_eeprom_write_page(hw, data, off, pg_len, intr))
+			return -1;
+
+		/* Otherwise go on to the next page */
+		len  -= pg_len;
+		off  += pg_len;
+		data += pg_len;
+	}
+
+	/* Wait for the last write to complete */
+	if (e1000_spi_eeprom_poll_ready(hw, intr))
+		return -1;
+
+	/* We're done! */
+	return 0;
+}
+
+static int do_e1000_spi_show(cmd_tbl_t *cmdtp, struct e1000_hw *hw,
+		int argc, char * const argv[])
+{
+	unsigned int length = 0;
+	u16 i, offset = 0;
+	u8 *buffer;
+	int err;
+
+	if (argc > 2) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* Parse the offset and length */
+	if (argc >= 1)
+		offset = simple_strtoul(argv[0], NULL, 0);
+	if (argc == 2)
+		length = simple_strtoul(argv[1], NULL, 0);
+	else if (offset < (hw->eeprom.word_size << 1))
+		length = (hw->eeprom.word_size << 1) - offset;
+
+	/* Extra sanity checks */
+	if (!length) {
+		E1000_ERR(hw->nic, "Requested zero-sized dump!\n");
+		return 1;
+	}
+	if ((0x10000 < length) || (0x10000 - length < offset)) {
+		E1000_ERR(hw->nic, "Can't dump past 0xFFFF!\n");
+		return 1;
+	}
+
+	/* Allocate a buffer to hold stuff */
+	buffer = malloc(length);
+	if (!buffer) {
+		E1000_ERR(hw->nic, "Out of Memory!\n");
+		return 1;
+	}
+
+	/* Acquire the EEPROM and perform the dump */
+	if (e1000_acquire_eeprom(hw)) {
+		E1000_ERR(hw->nic, "EEPROM SPI cannot be acquired!\n");
+		free(buffer);
+		return 1;
+	}
+	err = e1000_spi_eeprom_dump(hw, buffer, offset, length, TRUE);
+	e1000_release_eeprom(hw);
+	if (err) {
+		E1000_ERR(hw->nic, "Interrupted!\n");
+		free(buffer);
+		return 1;
+	}
+
+	/* Now hexdump the result */
+	printf("%s: ===== Intel e1000 EEPROM (0x%04hX - 0x%04hX) =====",
+			hw->nic->name, offset, offset + length - 1);
+	for (i = 0; i < length; i++) {
+		if ((i & 0xF) == 0)
+			printf("\n%s: %04hX: ", hw->nic->name, offset + i);
+		else if ((i & 0xF) == 0x8)
+			printf(" ");
+		printf(" %02hx", buffer[i]);
+	}
+	printf("\n");
+
+	/* Success! */
+	free(buffer);
+	return 0;
+}
+
+static int do_e1000_spi_dump(cmd_tbl_t *cmdtp, struct e1000_hw *hw,
+		int argc, char * const argv[])
+{
+	unsigned int length;
+	u16 offset;
+	void *dest;
+
+	if (argc != 3) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* Parse the arguments */
+	dest = (void *)simple_strtoul(argv[0], NULL, 16);
+	offset = simple_strtoul(argv[1], NULL, 0);
+	length = simple_strtoul(argv[2], NULL, 0);
+
+	/* Extra sanity checks */
+	if (!length) {
+		E1000_ERR(hw->nic, "Requested zero-sized dump!\n");
+		return 1;
+	}
+	if ((0x10000 < length) || (0x10000 - length < offset)) {
+		E1000_ERR(hw->nic, "Can't dump past 0xFFFF!\n");
+		return 1;
+	}
+
+	/* Acquire the EEPROM */
+	if (e1000_acquire_eeprom(hw)) {
+		E1000_ERR(hw->nic, "EEPROM SPI cannot be acquired!\n");
+		return 1;
+	}
+
+	/* Perform the programming operation */
+	if (e1000_spi_eeprom_dump(hw, dest, offset, length, TRUE) < 0) {
+		E1000_ERR(hw->nic, "Interrupted!\n");
+		e1000_release_eeprom(hw);
+		return 1;
+	}
+
+	e1000_release_eeprom(hw);
+	printf("%s: ===== EEPROM DUMP COMPLETE =====\n", hw->nic->name);
+	return 0;
+}
+
+static int do_e1000_spi_program(cmd_tbl_t *cmdtp, struct e1000_hw *hw,
+		int argc, char * const argv[])
+{
+	unsigned int length;
+	const void *source;
+	u16 offset;
+
+	if (argc != 3) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* Parse the arguments */
+	source = (const void *)simple_strtoul(argv[0], NULL, 16);
+	offset = simple_strtoul(argv[1], NULL, 0);
+	length = simple_strtoul(argv[2], NULL, 0);
+
+	/* Acquire the EEPROM */
+	if (e1000_acquire_eeprom(hw)) {
+		E1000_ERR(hw->nic, "EEPROM SPI cannot be acquired!\n");
+		return 1;
+	}
+
+	/* Perform the programming operation */
+	if (e1000_spi_eeprom_program(hw, source, offset, length, TRUE) < 0) {
+		E1000_ERR(hw->nic, "Interrupted!\n");
+		e1000_release_eeprom(hw);
+		return 1;
+	}
+
+	e1000_release_eeprom(hw);
+	printf("%s: ===== EEPROM PROGRAMMED =====\n", hw->nic->name);
+	return 0;
+}
+
+static int do_e1000_spi_checksum(cmd_tbl_t *cmdtp, struct e1000_hw *hw,
+		int argc, char * const argv[])
+{
+	uint16_t i, length, checksum, checksum_reg;
+	uint16_t *buffer;
+	boolean_t upd;
+
+	if (argc == 0)
+		upd = 0;
+	else if ((argc == 1) && !strcmp(argv[0], "update"))
+		upd = 1;
+	else {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* Allocate a temporary buffer */
+	length = sizeof(uint16_t) * (EEPROM_CHECKSUM_REG + 1);
+	buffer = malloc(length);
+	if (!buffer) {
+		E1000_ERR(hw->nic, "Unable to allocate EEPROM buffer!\n");
+		return 1;
+	}
+
+	/* Acquire the EEPROM */
+	if (e1000_acquire_eeprom(hw)) {
+		E1000_ERR(hw->nic, "EEPROM SPI cannot be acquired!\n");
+		return 1;
+	}
+
+	/* Read the EEPROM */
+	if (e1000_spi_eeprom_dump(hw, buffer, 0, length, TRUE) < 0) {
+		E1000_ERR(hw->nic, "Interrupted!\n");
+		e1000_release_eeprom(hw);
+		return 1;
+	}
+
+	/* Compute the checksum and read the expected value */
+	for (i = 0; i < EEPROM_CHECKSUM_REG; i++)
+		checksum += le16_to_cpu(buffer[i]);
+	checksum = ((uint16_t)EEPROM_SUM) - checksum;
+	checksum_reg = le16_to_cpu(buffer[i]);
+
+	/* Verify it! */
+	if (checksum_reg == checksum) {
+		printf("%s: INFO: EEPROM checksum is correct! (0x%04hx)\n",
+				hw->nic->name, checksum);
+		e1000_release_eeprom(hw);
+		return 0;
+	}
+
+	/* Hrm, verification failed, print an error */
+	E1000_ERR(hw->nic, "EEPROM checksum is incorrect!\n");
+	E1000_ERR(hw->nic, "  ...register was 0x%04hx, calculated 0x%04hx\n",
+			checksum_reg, checksum);
+
+	/* If they didn't ask us to update it, just return an error */
+	if (!upd) {
+		e1000_release_eeprom(hw);
+		return 1;
+	}
+
+	/* Ok, correct it! */
+	printf("%s: Reprogramming the EEPROM checksum...\n", hw->nic->name);
+	buffer[i] = cpu_to_le16(checksum);
+	if (e1000_spi_eeprom_program(hw, &buffer[i], i * sizeof(uint16_t),
+			sizeof(uint16_t), TRUE)) {
+		E1000_ERR(hw->nic, "Interrupted!\n");
+		e1000_release_eeprom(hw);
+		return 1;
+	}
+
+	e1000_release_eeprom(hw);
+	return 0;
+}
+
+int do_e1000_spi(cmd_tbl_t *cmdtp, struct e1000_hw *hw,
+		int argc, char * const argv[])
+{
+	if (argc < 1) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* Make sure it has an SPI chip */
+	if (hw->eeprom.type != e1000_eeprom_spi) {
+		E1000_ERR(hw->nic, "No attached SPI EEPROM found!\n");
+		return 1;
+	}
+
+	/* Check the eeprom sub-sub-command arguments */
+	if (!strcmp(argv[0], "show"))
+		return do_e1000_spi_show(cmdtp, hw, argc - 1, argv + 1);
+
+	if (!strcmp(argv[0], "dump"))
+		return do_e1000_spi_dump(cmdtp, hw, argc - 1, argv + 1);
+
+	if (!strcmp(argv[0], "program"))
+		return do_e1000_spi_program(cmdtp, hw, argc - 1, argv + 1);
+
+	if (!strcmp(argv[0], "checksum"))
+		return do_e1000_spi_checksum(cmdtp, hw, argc - 1, argv + 1);
+
+	cmd_usage(cmdtp);
+	return 1;
+}
+
+#endif /* not CONFIG_CMD_E1000 */