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Code Issues Releases Wiki Activity

staging: mt7621-spi: drop the broken full-duplex mode

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According to John Crispin (aka blogic) on IRC on Nov 26 2018:
  so basically i made cs1 work for MTK/labs when i built
  the linkit smart for them. the req-sheet said that cs1 should be proper
  duplex spi. however ....
   1) the core will always send 1 byte before any transfer, this is the
      m25p80 command.
   2) mode 3 is broken and bit reversed (?)
   3) some bit are incorrectly wired in hw for mode2/3
  we wrote a test script and test for [0-0xffff] on all modes and certain
  bits are swizzled under certain conditions and it was not possible to
  fix this even using a hack.
  we then decided to use spi-gpio and i never removed the errornous code
  basically the spi is fecked for anything but half duplex spi mode0
  running a sflash on it

The controller will always send some data from OPCODE register under half
duplex mode before starting a full-duplex transfer, so the full-duplex
mode is broken.
This piece of code also make CS1 unavailable since it forces the
broken full-duplex mode to be used on CS1.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chuanhong Guo 2018-12-06 21:15:08 +08:00 committed by Greg Kroah-Hartman
parent d6a0de4933
commit 108d9dd513
1 changed files with 17 additions and 106 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

123
drivers/staging/mt7621-spi/spi-mt7621.c
View file

@ -86,16 +86,13 @@ static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
iowrite32(val, rs->base + reg);
}
static void mt7621_spi_reset(struct mt7621_spi *rs, int duplex)
static void mt7621_spi_reset(struct mt7621_spi *rs)
{
u32 master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
master |= 7 << 29;
master |= 1 << 2;
if (duplex)
master |= 1 << 10;
else
master &= ~(1 << 10);
master &= ~(1 << 10);
mt7621_spi_write(rs, MT7621_SPI_MASTER, master);
rs->pending_write = 0;
@ -107,7 +104,7 @@ static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
int cs = spi->chip_select;
u32 polar = 0;
mt7621_spi_reset(rs, cs);
mt7621_spi_reset(rs);
if (enable)
polar = BIT(cs);
mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
@ -261,7 +258,7 @@ static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs,
rs->pending_write = len;
}
static int mt7621_spi_transfer_half_duplex(struct spi_master *master,
static int mt7621_spi_transfer_one_message(struct spi_master *master,
struct spi_message *m)
{
struct mt7621_spi *rs = spi_master_get_devdata(master);
@ -284,10 +281,20 @@ static int mt7621_spi_transfer_half_duplex(struct spi_master *master,
mt7621_spi_set_cs(spi, 1);
m->actual_length = 0;
list_for_each_entry(t, &m->transfers, transfer_list) {
if (t->rx_buf)
if ((t->rx_buf) && (t->tx_buf)) {
/* This controller will shift some extra data out
* of spi_opcode if (mosi_bit_cnt > 0) &&
* (cmd_bit_cnt == 0). So the claimed full-duplex
* support is broken since we have no way to read
* the MISO value during that bit.
*/
status = -EIO;
goto msg_done;
} else if (t->rx_buf) {
mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf);
else if (t->tx_buf)
} else if (t->tx_buf) {
mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf);
}
m->actual_length += t->len;
}
mt7621_spi_flush(rs);
@ -300,102 +307,6 @@ static int mt7621_spi_transfer_half_duplex(struct spi_master *master,
return 0;
}
static int mt7621_spi_transfer_full_duplex(struct spi_master *master,
struct spi_message *m)
{
struct mt7621_spi *rs = spi_master_get_devdata(master);
struct spi_device *spi = m->spi;
unsigned int speed = spi->max_speed_hz;
struct spi_transfer *t = NULL;
int status = 0;
int i, len = 0;
int rx_len = 0;
u32 data[9] = { 0 };
u32 val = 0;
mt7621_spi_wait_till_ready(rs);
list_for_each_entry(t, &m->transfers, transfer_list) {
const u8 *buf = t->tx_buf;
if (t->rx_buf)
rx_len += t->len;
if (!buf)
continue;
if (WARN_ON(len + t->len > 16)) {
status = -EIO;
goto msg_done;
}
for (i = 0; i < t->len; i++, len++)
data[len / 4] |= buf[i] << (8 * (len & 3));
if (speed > t->speed_hz)
speed = t->speed_hz;
}
if (WARN_ON(rx_len > 16)) {
status = -EIO;
goto msg_done;
}
if (mt7621_spi_prepare(spi, speed)) {
status = -EIO;
goto msg_done;
}
for (i = 0; i < len; i += 4)
mt7621_spi_write(rs, MT7621_SPI_DATA0 + i, data[i / 4]);
val |= len * 8;
val |= (rx_len * 8) << 12;
mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
mt7621_spi_set_cs(spi, 1);
val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
val |= SPI_CTL_START;
mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
mt7621_spi_wait_till_ready(rs);
mt7621_spi_set_cs(spi, 0);
for (i = 0; i < rx_len; i += 4)
data[i / 4] = mt7621_spi_read(rs, MT7621_SPI_DATA4 + i);
m->actual_length = rx_len;
len = 0;
list_for_each_entry(t, &m->transfers, transfer_list) {
u8 *buf = t->rx_buf;
if (!buf)
continue;
for (i = 0; i < t->len; i++, len++)
buf[i] = data[len / 4] >> (8 * (len & 3));
}
msg_done:
m->status = status;
spi_finalize_current_message(master);
return 0;
}
static int mt7621_spi_transfer_one_message(struct spi_master *master,
struct spi_message *m)
{
struct spi_device *spi = m->spi;
int cs = spi->chip_select;
if (cs)
return mt7621_spi_transfer_full_duplex(master, m);
return mt7621_spi_transfer_half_duplex(master, m);
}
static int mt7621_spi_setup(struct spi_device *spi)
{
struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
@ -478,7 +389,7 @@ static int mt7621_spi_probe(struct platform_device *pdev)
device_reset(&pdev->dev);
mt7621_spi_reset(rs, 0);
mt7621_spi_reset(rs);
return spi_register_master(master);
}