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path: root/drivers/spi/exynos_spi.c
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Diffstat (limited to 'drivers/spi/exynos_spi.c')
-rw-r--r--drivers/spi/exynos_spi.c107
1 files changed, 88 insertions, 19 deletions
diff --git a/drivers/spi/exynos_spi.c b/drivers/spi/exynos_spi.c
index efc8b1e3a..699c57eb6 100644
--- a/drivers/spi/exynos_spi.c
+++ b/drivers/spi/exynos_spi.c
@@ -26,6 +26,7 @@ struct spi_bus {
struct exynos_spi *regs;
int inited; /* 1 if this bus is ready for use */
int node;
+ uint deactivate_delay_us; /* Delay to wait after deactivate */
};
/* A list of spi buses that we know about */
@@ -40,6 +41,8 @@ struct exynos_spi_slave {
enum periph_id periph_id; /* Peripheral ID for this device */
unsigned int fifo_size;
int skip_preamble;
+ struct spi_bus *bus; /* Pointer to our SPI bus info */
+ ulong last_transaction_us; /* Time of last transaction end */
};
static struct spi_bus *spi_get_bus(unsigned dev_index)
@@ -85,6 +88,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs,
}
bus = &spi_bus[busnum];
+ spi_slave->bus = bus;
spi_slave->regs = bus->regs;
spi_slave->mode = mode;
spi_slave->periph_id = bus->periph_id;
@@ -95,6 +99,7 @@ struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs,
spi_slave->fifo_size = 256;
spi_slave->skip_preamble = 0;
+ spi_slave->last_transaction_us = timer_get_us();
spi_slave->freq = bus->frequency;
if (max_hz)
@@ -199,12 +204,29 @@ static void spi_get_fifo_levels(struct exynos_spi *regs,
*
* @param regs SPI peripheral registers
* @param count Number of bytes to transfer
+ * @param step Number of bytes to transfer in each packet (1 or 4)
*/
-static void spi_request_bytes(struct exynos_spi *regs, int count)
+static void spi_request_bytes(struct exynos_spi *regs, int count, int step)
{
+ /* For word address we need to swap bytes */
+ if (step == 4) {
+ setbits_le32(&regs->mode_cfg,
+ SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD);
+ count /= 4;
+ setbits_le32(&regs->swap_cfg, SPI_TX_SWAP_EN | SPI_RX_SWAP_EN |
+ SPI_TX_BYTE_SWAP | SPI_RX_BYTE_SWAP |
+ SPI_TX_HWORD_SWAP | SPI_RX_HWORD_SWAP);
+ } else {
+ /* Select byte access and clear the swap configuration */
+ clrbits_le32(&regs->mode_cfg,
+ SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD);
+ writel(0, &regs->swap_cfg);
+ }
+
assert(count && count < (1 << 16));
setbits_le32(&regs->ch_cfg, SPI_CH_RST);
clrbits_le32(&regs->ch_cfg, SPI_CH_RST);
+
writel(count | SPI_PACKET_CNT_EN, &regs->pkt_cnt);
}
@@ -219,6 +241,7 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo,
int toread;
unsigned start = get_timer(0);
int stopping;
+ int step;
out_bytes = in_bytes = todo;
@@ -226,10 +249,19 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo,
!(spi_slave->mode & SPI_SLAVE);
/*
+ * Try to transfer words if we can. This helps read performance at
+ * SPI clock speeds above about 20MHz.
+ */
+ step = 1;
+ if (!((todo | (uintptr_t)rxp | (uintptr_t)txp) & 3) &&
+ !spi_slave->skip_preamble)
+ step = 4;
+
+ /*
* If there's something to send, do a software reset and set a
* transaction size.
*/
- spi_request_bytes(regs, todo);
+ spi_request_bytes(regs, todo, step);
/*
* Bytes are transmitted/received in pairs. Wait to receive all the
@@ -242,24 +274,42 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo,
/* Keep the fifos full/empty. */
spi_get_fifo_levels(regs, &rx_lvl, &tx_lvl);
- if (tx_lvl < spi_slave->fifo_size && out_bytes) {
- temp = txp ? *txp++ : 0xff;
+
+ /*
+ * Don't completely fill the txfifo, since we don't want our
+ * rxfifo to overflow, and it may already contain data.
+ */
+ while (tx_lvl < spi_slave->fifo_size/2 && out_bytes) {
+ if (!txp)
+ temp = -1;
+ else if (step == 4)
+ temp = *(uint32_t *)txp;
+ else
+ temp = *txp;
writel(temp, &regs->tx_data);
- out_bytes--;
+ out_bytes -= step;
+ if (txp)
+ txp += step;
+ tx_lvl += step;
}
- if (rx_lvl > 0) {
- temp = readl(&regs->rx_data);
- if (spi_slave->skip_preamble) {
- if (temp == SPI_PREAMBLE_END_BYTE) {
- spi_slave->skip_preamble = 0;
- stopping = 0;
+ if (rx_lvl >= step) {
+ while (rx_lvl >= step) {
+ temp = readl(&regs->rx_data);
+ if (spi_slave->skip_preamble) {
+ if (temp == SPI_PREAMBLE_END_BYTE) {
+ spi_slave->skip_preamble = 0;
+ stopping = 0;
+ }
+ } else {
+ if (rxp || stopping) {
+ *rxp = temp;
+ rxp += step;
+ }
+ in_bytes -= step;
}
- } else {
- if (rxp || stopping)
- *rxp++ = temp;
- in_bytes--;
+ toread -= step;
+ rx_lvl -= step;
}
- toread--;
} else if (!toread) {
/*
* We have run out of input data, but haven't read
@@ -271,7 +321,7 @@ static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo,
out_bytes = in_bytes;
toread = in_bytes;
txp = NULL;
- spi_request_bytes(regs, toread);
+ spi_request_bytes(regs, toread, step);
}
if (spi_slave->skip_preamble && get_timer(start) > 100) {
printf("SPI timeout: in_bytes=%d, out_bytes=%d, ",
@@ -315,10 +365,14 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
if ((flags & SPI_XFER_BEGIN))
spi_cs_activate(slave);
- /* Exynos SPI limits each transfer to 65535 bytes */
+ /*
+ * Exynos SPI limits each transfer to 65535 transfers. To keep
+ * things simple, allow a maximum of 65532 bytes. We could allow
+ * more in word mode, but the performance difference is small.
+ */
bytelen = bitlen / 8;
for (upto = 0; !ret && upto < bytelen; upto += todo) {
- todo = min(bytelen - upto, (1 << 16) - 1);
+ todo = min(bytelen - upto, (1 << 16) - 4);
ret = spi_rx_tx(spi_slave, todo, &din, &dout, flags);
if (ret)
break;
@@ -359,9 +413,22 @@ void spi_cs_activate(struct spi_slave *slave)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
+ /* If it's too soon to do another transaction, wait */
+ if (spi_slave->bus->deactivate_delay_us &&
+ spi_slave->last_transaction_us) {
+ ulong delay_us; /* The delay completed so far */
+ delay_us = timer_get_us() - spi_slave->last_transaction_us;
+ if (delay_us < spi_slave->bus->deactivate_delay_us)
+ udelay(spi_slave->bus->deactivate_delay_us - delay_us);
+ }
+
clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
debug("Activate CS, bus %d\n", spi_slave->slave.bus);
spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
+
+ /* Remember time of this transaction so we can honour the bus delay */
+ if (spi_slave->bus->deactivate_delay_us)
+ spi_slave->last_transaction_us = timer_get_us();
}
/**
@@ -411,6 +478,8 @@ static int spi_get_config(const void *blob, int node, struct spi_bus *bus)
/* Use 500KHz as a suitable default */
bus->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
500000);
+ bus->deactivate_delay_us = fdtdec_get_int(blob, node,
+ "spi-deactivate-delay", 0);
return 0;
}
generated by cgit v1.2.3-70-g09d2 (git 2.51.2) at 2025-10-31 19:04:23 +0000