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u-boot/drivers/spi/bfin_spi.c
Todor I Mollov d04371a116 Blackfin: spi: make cs deassert function deterministic 
Blackfin SPI driver was not driving the SPI chip-select high before
putting the chip-select signals into tri-state mode.  This is probably
something that slipped by unnoticed in most designs.  If the signals are
put directly into a tri-state mode, then the board is relying on the
pull-up resistors to pull up the chip-select before the next transaction.
Most of the time this is fine, except when you have two transactions that
follow each other very closely, such as the flash erase and read status
register commands.  In this case I was seeing a 500ns separation between
the transactions.  In my setup, with a 10kOhm pull-up, it would meet
timing spec about half the time and resulted in intermittent errors.  (A
stronger pull up would fix this, but our design is targeted for low power
consumption and a 3.3kOhm @ 3.3v is 3.3mW of needless power consumption.)
I modified the spi_cs_deactivate() function in bfin_spi.c to drive the
chip-selects high before putting them into tri-state.  For me, this
resulted in a rise time of 5ns instead of the previous rise time of about
1us, and fully satisfied the timing spec of the chip.

Signed-off-by: Todor I Mollov <tmollov@ucsd.edu>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-04-06 03:49:31 -04:00

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/*
* Driver for Blackfin On-Chip SPI device
*
* Copyright (c) 2005-2008 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
/*#define DEBUG*/
#include <common.h>
#include <malloc.h>
#include <spi.h>
#include <asm/blackfin.h>
#include <asm/mach-common/bits/spi.h>
struct bfin_spi_slave {
struct spi_slave slave;
void *mmr_base;
u16 ctl, baud, flg;
};
#define MAKE_SPI_FUNC(mmr, off) \
static inline void write_##mmr(struct bfin_spi_slave *bss, u16 val) { bfin_write16(bss->mmr_base + off, val); } \
static inline u16 read_##mmr(struct bfin_spi_slave *bss) { return bfin_read16(bss->mmr_base + off); }
MAKE_SPI_FUNC(SPI_CTL, 0x00)
MAKE_SPI_FUNC(SPI_FLG, 0x04)
MAKE_SPI_FUNC(SPI_STAT, 0x08)
MAKE_SPI_FUNC(SPI_TDBR, 0x0c)
MAKE_SPI_FUNC(SPI_RDBR, 0x10)
MAKE_SPI_FUNC(SPI_BAUD, 0x14)
#define to_bfin_spi_slave(s) container_of(s, struct bfin_spi_slave, slave)
__attribute__((weak))
int spi_cs_is_valid(unsigned int bus, unsigned int cs)
{
#if defined(__ADSPBF538__) || defined(__ADSPBF539__)
/* The SPI1/SPI2 buses are weird ... only 1 CS */
if (bus > 0 && cs != 1)
return 0;
#endif
return (cs >= 1 && cs <= 7);
}
__attribute__((weak))
void spi_cs_activate(struct spi_slave *slave)
{
struct bfin_spi_slave *bss = to_bfin_spi_slave(slave);
write_SPI_FLG(bss,
(read_SPI_FLG(bss) &
~((!bss->flg << 8) << slave->cs)) |
(1 << slave->cs));
SSYNC();
debug("%s: SPI_FLG:%x\n", __func__, read_SPI_FLG(bss));
}
__attribute__((weak))
void spi_cs_deactivate(struct spi_slave *slave)
{
struct bfin_spi_slave *bss = to_bfin_spi_slave(slave);
u16 flg;
/* make sure we force the cs to deassert rather than let the
* pin float back up. otherwise, exact timings may not be
* met some of the time leading to random behavior (ugh).
*/
flg = read_SPI_FLG(bss) | ((!bss->flg << 8) << slave->cs);
write_SPI_FLG(bss, flg);
SSYNC();
debug("%s: SPI_FLG:%x\n", __func__, read_SPI_FLG(bss));
flg &= ~(1 << slave->cs);
write_SPI_FLG(bss, flg);
SSYNC();
debug("%s: SPI_FLG:%x\n", __func__, read_SPI_FLG(bss));
}
void spi_init()
{
}
struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
struct bfin_spi_slave *bss;
u32 mmr_base;
u32 baud;
if (!spi_cs_is_valid(bus, cs))
return NULL;
switch (bus) {
#ifdef SPI_CTL
# define SPI0_CTL SPI_CTL
#endif
case 0: mmr_base = SPI0_CTL; break;
#ifdef SPI1_CTL
case 1: mmr_base = SPI1_CTL; break;
#endif
#ifdef SPI2_CTL
case 2: mmr_base = SPI2_CTL; break;
#endif
default: return NULL;
}
baud = get_sclk() / (2 * max_hz);
if (baud < 2)
baud = 2;
else if (baud > (u16)-1)
baud = -1;
bss = malloc(sizeof(*bss));
if (!bss)
return NULL;
bss->slave.bus = bus;
bss->slave.cs = cs;
bss->mmr_base = (void *)mmr_base;
bss->ctl = SPE | MSTR | TDBR_CORE;
if (mode & SPI_CPHA) bss->ctl |= CPHA;
if (mode & SPI_CPOL) bss->ctl |= CPOL;
if (mode & SPI_LSB_FIRST) bss->ctl |= LSBF;
bss->baud = baud;
bss->flg = mode & SPI_CS_HIGH ? 1 : 0;
debug("%s: bus:%i cs:%i mmr:%x ctl:%x baud:%i flg:%i\n", __func__,
bus, cs, mmr_base, bss->ctl, baud, bss->flg);
return &bss->slave;
}
void spi_free_slave(struct spi_slave *slave)
{
struct bfin_spi_slave *bss = to_bfin_spi_slave(slave);
free(bss);
}
static void spi_portmux(struct spi_slave *slave)
{
#if defined(__ADSPBF51x__)
#define SET_MUX(port, mux, func) port##_mux = ((port##_mux & ~PORT_x_MUX_##mux##_MASK) | PORT_x_MUX_##mux##_FUNC_##func)
u16 f_mux = bfin_read_PORTF_MUX();
u16 f_fer = bfin_read_PORTF_FER();
u16 g_mux = bfin_read_PORTG_MUX();
u16 g_fer = bfin_read_PORTG_FER();
u16 h_mux = bfin_read_PORTH_MUX();
u16 h_fer = bfin_read_PORTH_FER();
switch (slave->bus) {
case 0:
/* set SCK/MISO/MOSI */
SET_MUX(g, 7, 1);
g_fer |= PG12 | PG13 | PG14;
switch (slave->cs) {
case 1: SET_MUX(f, 2, 1); f_fer |= PF7; break;
case 2: /* see G above */ g_fer |= PG15; break;
case 3: SET_MUX(h, 1, 3); f_fer |= PH4; break;
case 4: /* no muxing */ break;
case 5: SET_MUX(g, 1, 3); h_fer |= PG3; break;
case 6: /* no muxing */ break;
case 7: /* no muxing */ break;
}
case 1:
/* set SCK/MISO/MOSI */
SET_MUX(h, 0, 2);
h_fer |= PH1 | PH2 | PH3;
switch (slave->cs) {
case 1: SET_MUX(h, 2, 3); h_fer |= PH6; break;
case 2: SET_MUX(f, 0, 3); f_fer |= PF0; break;
case 3: SET_MUX(g, 0, 3); g_fer |= PG0; break;
case 4: SET_MUX(f, 3, 3); f_fer |= PF8; break;
case 5: SET_MUX(g, 6, 3); h_fer |= PG11; break;
case 6: /* no muxing */ break;
case 7: /* no muxing */ break;
}
}
bfin_write_PORTF_MUX(f_mux);
bfin_write_PORTF_FER(f_fer);
bfin_write_PORTG_MUX(g_mux);
bfin_write_PORTG_FER(g_fer);
bfin_write_PORTH_MUX(h_mux);
bfin_write_PORTH_FER(h_fer);
#elif defined(__ADSPBF52x__)
#define SET_MUX(port, mux, func) port##_mux = ((port##_mux & ~PORT_x_MUX_##mux##_MASK) | PORT_x_MUX_##mux##_FUNC_##func)
u16 f_mux = bfin_read_PORTF_MUX();
u16 f_fer = bfin_read_PORTF_FER();
u16 g_mux = bfin_read_PORTG_MUX();
u16 g_fer = bfin_read_PORTG_FER();
u16 h_mux = bfin_read_PORTH_MUX();
u16 h_fer = bfin_read_PORTH_FER();
/* set SCK/MISO/MOSI */
SET_MUX(g, 0, 3);
g_fer |= PG2 | PG3 | PG4;
switch (slave->cs) {
case 1: /* see G above */ g_fer |= PG1; break;
case 2: SET_MUX(f, 4, 3); f_fer |= PF12; break;
case 3: SET_MUX(f, 4, 3); f_fer |= PF13; break;
case 4: SET_MUX(h, 1, 1); h_fer |= PH8; break;
case 5: SET_MUX(h, 2, 1); h_fer |= PH9; break;
case 6: SET_MUX(f, 1, 3); f_fer |= PF9; break;
case 7: SET_MUX(f, 2, 3); f_fer |= PF10; break;
}
bfin_write_PORTF_MUX(f_mux);
bfin_write_PORTF_FER(f_fer);
bfin_write_PORTG_MUX(g_mux);
bfin_write_PORTG_FER(g_fer);
bfin_write_PORTH_MUX(h_mux);
bfin_write_PORTH_FER(h_fer);
#elif defined(__ADSPBF534__) || defined(__ADSPBF536__) || defined(__ADSPBF537__)
u16 mux = bfin_read_PORT_MUX();
u16 f_fer = bfin_read_PORTF_FER();
/* set SCK/MISO/MOSI */
f_fer |= PF11 | PF12 | PF13;
switch (slave->cs) {
case 1: f_fer |= PF10; break;
case 2: mux |= PJSE; break;
case 3: mux |= PJSE; break;
case 4: mux |= PFS4E; f_fer |= PF6; break;
case 5: mux |= PFS5E; f_fer |= PF5; break;
case 6: mux |= PFS6E; f_fer |= PF4; break;
case 7: mux |= PJCE_SPI; break;
}
bfin_write_PORT_MUX(mux);
bfin_write_PORTF_FER(f_fer);
#elif defined(__ADSPBF538__) || defined(__ADSPBF539__)
u16 fer, pins;
if (slave->bus == 1)
pins = PD0 | PD1 | PD2 | (slave->cs == 1 ? PD4 : 0);
else if (slave->bus == 2)
pins = PD5 | PD6 | PD7 | (slave->cs == 1 ? PD9 : 0);
else
pins = 0;
if (pins) {
fer = bfin_read_PORTDIO_FER();
fer &= ~pins;
bfin_write_PORTDIO_FER(fer);
}
#elif defined(__ADSPBF54x__)
#define DO_MUX(port, pin) \
mux = ((mux & ~PORT_x_MUX_##pin##_MASK) | PORT_x_MUX_##pin##_FUNC_1); \
fer |= P##port##pin;
u32 mux;
u16 fer;
switch (slave->bus) {
case 0:
mux = bfin_read_PORTE_MUX();
fer = bfin_read_PORTE_FER();
/* set SCK/MISO/MOSI */
DO_MUX(E, 0);
DO_MUX(E, 1);
DO_MUX(E, 2);
switch (slave->cs) {
case 1: DO_MUX(E, 4); break;
case 2: DO_MUX(E, 5); break;
case 3: DO_MUX(E, 6); break;
}
bfin_write_PORTE_MUX(mux);
bfin_write_PORTE_FER(fer);
break;
case 1:
mux = bfin_read_PORTG_MUX();
fer = bfin_read_PORTG_FER();
/* set SCK/MISO/MOSI */
DO_MUX(G, 8);
DO_MUX(G, 9);
DO_MUX(G, 10);
switch (slave->cs) {
case 1: DO_MUX(G, 5); break;
case 2: DO_MUX(G, 6); break;
case 3: DO_MUX(G, 7); break;
}
bfin_write_PORTG_MUX(mux);
bfin_write_PORTG_FER(fer);
break;
case 2:
mux = bfin_read_PORTB_MUX();
fer = bfin_read_PORTB_FER();
/* set SCK/MISO/MOSI */
DO_MUX(B, 12);
DO_MUX(B, 13);
DO_MUX(B, 14);
switch (slave->cs) {
case 1: DO_MUX(B, 9); break;
case 2: DO_MUX(B, 10); break;
case 3: DO_MUX(B, 11); break;
}
bfin_write_PORTB_MUX(mux);
bfin_write_PORTB_FER(fer);
break;
}
#endif
}
int spi_claim_bus(struct spi_slave *slave)
{
struct bfin_spi_slave *bss = to_bfin_spi_slave(slave);
debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
spi_portmux(slave);
write_SPI_CTL(bss, bss->ctl);
write_SPI_BAUD(bss, bss->baud);
SSYNC();
return 0;
}
void spi_release_bus(struct spi_slave *slave)
{
struct bfin_spi_slave *bss = to_bfin_spi_slave(slave);
debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
write_SPI_CTL(bss, 0);
SSYNC();
}
int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
void *din, unsigned long flags)
{
struct bfin_spi_slave *bss = to_bfin_spi_slave(slave);
const u8 *tx = dout;
u8 *rx = din;
uint bytes = bitlen / 8;
int ret = 0;
debug("%s: bus:%i cs:%i bitlen:%i bytes:%i flags:%lx\n", __func__,
slave->bus, slave->cs, bitlen, bytes, flags);
if (bitlen == 0)
goto done;
/* we can only do 8 bit transfers */
if (bitlen % 8) {
flags |= SPI_XFER_END;
goto done;
}
if (flags & SPI_XFER_BEGIN)
spi_cs_activate(slave);
/* todo: take advantage of hardware fifos and setup RX dma */
while (bytes--) {
u8 value = (tx ? *tx++ : 0);
debug("%s: tx:%x ", __func__, value);
write_SPI_TDBR(bss, value);
SSYNC();
while ((read_SPI_STAT(bss) & TXS))
if (ctrlc()) {
ret = -1;
goto done;
}
while (!(read_SPI_STAT(bss) & SPIF))
if (ctrlc()) {
ret = -1;
goto done;
}
while (!(read_SPI_STAT(bss) & RXS))
if (ctrlc()) {
ret = -1;
goto done;
}
value = read_SPI_RDBR(bss);
if (rx)
*rx++ = value;
debug("rx:%x\n", value);
}
done:
if (flags & SPI_XFER_END)
spi_cs_deactivate(slave);
return ret;
}
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