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Code Issues Releases Wiki Activity

Use caching for Nvidia MCP SPI GPIO accesses

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Reduce clock delay to zero.

Tests show more than 2x speedup.

Corresponding to flashrom svn r1164.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Tested-by: Andrew Morgan <ziltro@ziltro.com>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
This commit is contained in:
Carl-Daniel Hailfinger 2010-09-14 01:29:49 +00:00
parent 4b933f0c5e
commit 7b61df80fb
1 changed files with 25 additions and 35 deletions
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60
mcp6x_spi.c
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@ -42,41 +42,39 @@
void *mcp6x_spibar = NULL; void *mcp6x_spibar = NULL;
/* Cached value of last GPIO state. */
static uint8_t mcp_gpiostate;
static void mcp6x_request_spibus(void) static void mcp6x_request_spibus(void)
{ {
uint8_t tmp; mcp_gpiostate = mmio_readb(mcp6x_spibar + 0x530);
mcp_gpiostate |= 1 << MCP6X_SPI_REQUEST;
tmp = mmio_readb(mcp6x_spibar + 0x530); mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
tmp |= 1 << MCP6X_SPI_REQUEST;
mmio_writeb(tmp, mcp6x_spibar + 0x530);
/* Wait until we are allowed to use the SPI bus. */ /* Wait until we are allowed to use the SPI bus. */
while (!(mmio_readw(mcp6x_spibar + 0x530) & (1 << MCP6X_SPI_GRANT))) ; while (!(mmio_readw(mcp6x_spibar + 0x530) & (1 << MCP6X_SPI_GRANT))) ;
/* Update the cache. */
mcp_gpiostate = mmio_readb(mcp6x_spibar + 0x530);
} }
static void mcp6x_release_spibus(void) static void mcp6x_release_spibus(void)
{ {
uint8_t tmp; mcp_gpiostate &= ~(1 << MCP6X_SPI_REQUEST);
mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
tmp = mmio_readb(mcp6x_spibar + 0x530);
tmp &= ~(1 << MCP6X_SPI_REQUEST);
mmio_writeb(tmp, mcp6x_spibar + 0x530);
} }
static void mcp6x_bitbang_set_cs(int val) static void mcp6x_bitbang_set_cs(int val)
{ {
uint8_t tmp;
/* Requesting and releasing the SPI bus is handled in here to allow the /* Requesting and releasing the SPI bus is handled in here to allow the
* chipset to use its own SPI engine for native reads. * chipset to use its own SPI engine for native reads.
*/ */
if (val == 0) if (val == 0)
mcp6x_request_spibus(); mcp6x_request_spibus();
tmp = mmio_readb(mcp6x_spibar + 0x530); mcp_gpiostate &= ~(1 << MCP6X_SPI_CS);
tmp &= ~(1 << MCP6X_SPI_CS); mcp_gpiostate |= (val << MCP6X_SPI_CS);
tmp |= (val << MCP6X_SPI_CS); mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
mmio_writeb(tmp, mcp6x_spibar + 0x530);
if (val == 1) if (val == 1)
mcp6x_release_spibus(); mcp6x_release_spibus();
@ -84,31 +82,22 @@ static void mcp6x_bitbang_set_cs(int val)
static void mcp6x_bitbang_set_sck(int val) static void mcp6x_bitbang_set_sck(int val)
{ {
uint8_t tmp; mcp_gpiostate &= ~(1 << MCP6X_SPI_SCK);
mcp_gpiostate |= (val << MCP6X_SPI_SCK);
tmp = mmio_readb(mcp6x_spibar + 0x530); mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
tmp &= ~(1 << MCP6X_SPI_SCK);
tmp |= (val << MCP6X_SPI_SCK);
mmio_writeb(tmp, mcp6x_spibar + 0x530);
} }
static void mcp6x_bitbang_set_mosi(int val) static void mcp6x_bitbang_set_mosi(int val)
{ {
uint8_t tmp; mcp_gpiostate &= ~(1 << MCP6X_SPI_MOSI);
mcp_gpiostate |= (val << MCP6X_SPI_MOSI);
tmp = mmio_readb(mcp6x_spibar + 0x530); mmio_writeb(mcp_gpiostate, mcp6x_spibar + 0x530);
tmp &= ~(1 << MCP6X_SPI_MOSI);
tmp |= (val << MCP6X_SPI_MOSI);
mmio_writeb(tmp, mcp6x_spibar + 0x530);
} }
static int mcp6x_bitbang_get_miso(void) static int mcp6x_bitbang_get_miso(void)
{ {
uint8_t tmp; mcp_gpiostate = mmio_readb(mcp6x_spibar + 0x530);
return (mcp_gpiostate >> MCP6X_SPI_MISO) & 0x1;
tmp = mmio_readb(mcp6x_spibar + 0x530);
tmp = (tmp >> MCP6X_SPI_MISO) & 0x1;
return tmp;
} }
static const struct bitbang_spi_master bitbang_spi_master_mcp6x = { static const struct bitbang_spi_master bitbang_spi_master_mcp6x = {
@ -176,9 +165,10 @@ int mcp6x_spi_init(int want_spi)
msg_pdbg("SPI control is 0x%04x, req=%i, gnt=%i\n", msg_pdbg("SPI control is 0x%04x, req=%i, gnt=%i\n",
status, (status >> MCP6X_SPI_REQUEST) & 0x1, status, (status >> MCP6X_SPI_REQUEST) & 0x1,
(status >> MCP6X_SPI_GRANT) & 0x1); (status >> MCP6X_SPI_GRANT) & 0x1);
mcp_gpiostate = status & 0xff;
/* 1 usec halfperiod delay for now. */ /* Zero halfperiod delay. */
if (bitbang_spi_init(&bitbang_spi_master_mcp6x, 1)) { if (bitbang_spi_init(&bitbang_spi_master_mcp6x, 0)) {
/* This should never happen. */ /* This should never happen. */
msg_perr("MCP6X bitbang SPI master init failed!\n"); msg_perr("MCP6X bitbang SPI master init failed!\n");
return 1; return 1;