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Date: Fri, 17 Nov 2023 14:13:05 -0600
From: David Lechner <dlechner@...libre.com>
To: linux-spi@...r.kernel.org, devicetree@...r.kernel.org
Cc: David Lechner <dlechner@...libre.com>,
Mark Brown <broonie@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Nuno Sá <nuno.sa@...log.com>,
Lars-Peter Clausen <lars@...afoo.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH 14/14] spi: axi-spi-engine: add support for any word size
The AXI SPI Engine IP supports any word size from 1 to 32 bits. This
adds support for this by setting the bits_per_word_mask and emitting
the appropriate instruction to the SPI Engine each time a transfer
requires a new word size.
The functions that transfer tx/rx buffers from/to the SPI Engine
registers (spi_engine_write_{tx,rx}_fifo()) as well as the function that
creates the transfer instruction (spi_engine_gen_xfer()) also have to be
modified to take into account the word size since xfer->len is the
size of the buffers in bytes rather than words.
Signed-off-by: David Lechner <dlechner@...libre.com>
---
drivers/spi/spi-axi-spi-engine.c | 84 ++++++++++++++++++++++++++++++++--------
1 file changed, 68 insertions(+), 16 deletions(-)
diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c
index 1c60e6486ee2..cbca783830ea 100644
--- a/drivers/spi/spi-axi-spi-engine.c
+++ b/drivers/spi/spi-axi-spi-engine.c
@@ -53,6 +53,7 @@
#define SPI_ENGINE_CMD_REG_CLK_DIV 0x0
#define SPI_ENGINE_CMD_REG_CONFIG 0x1
+#define SPI_ENGINE_CMD_REG_XFER_BITS 0x2
#define SPI_ENGINE_MISC_SYNC 0x0
#define SPI_ENGINE_MISC_SLEEP 0x1
@@ -157,7 +158,14 @@ static unsigned int spi_engine_get_clk_div(struct spi_engine *spi_engine,
static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry,
struct spi_transfer *xfer)
{
- unsigned int len = xfer->len;
+ unsigned int len;
+
+ if (xfer->bits_per_word <= 8)
+ len = xfer->len;
+ else if (xfer->bits_per_word <= 16)
+ len = xfer->len / 2;
+ else
+ len = xfer->len / 4;
while (len) {
unsigned int n = min(len, 256U);
@@ -217,6 +225,7 @@ static int spi_engine_compile_message(struct spi_engine *spi_engine,
struct spi_transfer *xfer;
int clk_div, new_clk_div;
bool keep_cs = false;
+ u8 bits_per_word = 0;
clk_div = -1;
@@ -236,6 +245,13 @@ static int spi_engine_compile_message(struct spi_engine *spi_engine,
clk_div));
}
+ if (bits_per_word != xfer->bits_per_word) {
+ bits_per_word = xfer->bits_per_word;
+ spi_engine_program_add_cmd(p, dry,
+ SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_XFER_BITS,
+ bits_per_word));
+ }
+
spi_engine_gen_xfer(p, dry, xfer);
spi_engine_gen_sleep(p, dry, spi_engine, clk_div, xfer);
@@ -342,16 +358,34 @@ static bool spi_engine_write_tx_fifo(struct spi_engine *spi_engine,
void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDO_DATA_FIFO;
struct spi_engine_message_state *st = msg->state;
unsigned int n, m, i;
- const uint8_t *buf;
n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDO_FIFO_ROOM);
while (n && st->tx_length) {
- m = min(n, st->tx_length);
- buf = st->tx_buf;
- for (i = 0; i < m; i++)
- writel_relaxed(buf[i], addr);
- st->tx_buf += m;
- st->tx_length -= m;
+ if (st->tx_xfer->bits_per_word <= 8) {
+ const u8 *buf = st->tx_buf;
+
+ m = min(n, st->tx_length);
+ for (i = 0; i < m; i++)
+ writel_relaxed(buf[i], addr);
+ st->tx_buf += m;
+ st->tx_length -= m;
+ } else if (st->tx_xfer->bits_per_word <= 16) {
+ const u16 *buf = (const u16 *)st->tx_buf;
+
+ m = min(n, st->tx_length / 2);
+ for (i = 0; i < m; i++)
+ writel_relaxed(buf[i], addr);
+ st->tx_buf += m * 2;
+ st->tx_length -= m * 2;
+ } else {
+ const u32 *buf = (const u32 *)st->tx_buf;
+
+ m = min(n, st->tx_length / 4);
+ for (i = 0; i < m; i++)
+ writel_relaxed(buf[i], addr);
+ st->tx_buf += m * 4;
+ st->tx_length -= m * 4;
+ }
n -= m;
if (st->tx_length == 0)
spi_engine_tx_next(msg);
@@ -366,16 +400,34 @@ static bool spi_engine_read_rx_fifo(struct spi_engine *spi_engine,
void __iomem *addr = spi_engine->base + SPI_ENGINE_REG_SDI_DATA_FIFO;
struct spi_engine_message_state *st = msg->state;
unsigned int n, m, i;
- uint8_t *buf;
n = readl_relaxed(spi_engine->base + SPI_ENGINE_REG_SDI_FIFO_LEVEL);
while (n && st->rx_length) {
- m = min(n, st->rx_length);
- buf = st->rx_buf;
- for (i = 0; i < m; i++)
- buf[i] = readl_relaxed(addr);
- st->rx_buf += m;
- st->rx_length -= m;
+ if (st->rx_xfer->bits_per_word <= 8) {
+ u8 *buf = st->rx_buf;
+
+ m = min(n, st->rx_length);
+ for (i = 0; i < m; i++)
+ buf[i] = readl_relaxed(addr);
+ st->rx_buf += m;
+ st->rx_length -= m;
+ } else if (st->rx_xfer->bits_per_word <= 16) {
+ u16 *buf = (u16 *)st->rx_buf;
+
+ m = min(n, st->rx_length / 2);
+ for (i = 0; i < m; i++)
+ buf[i] = readl_relaxed(addr);
+ st->rx_buf += m * 2;
+ st->rx_length -= m * 2;
+ } else {
+ u32 *buf = (u32 *)st->rx_buf;
+
+ m = min(n, st->rx_length / 4);
+ for (i = 0; i < m; i++)
+ buf[i] = readl_relaxed(addr);
+ st->rx_buf += m * 4;
+ st->rx_length -= m * 4;
+ }
n -= m;
if (st->rx_length == 0)
spi_engine_rx_next(msg);
@@ -596,7 +648,7 @@ static int spi_engine_probe(struct platform_device *pdev)
host->dev.of_node = pdev->dev.of_node;
host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_3WIRE;
- host->bits_per_word_mask = SPI_BPW_MASK(8);
+ host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
host->max_speed_hz = clk_get_rate(spi_engine->ref_clk) / 2;
host->transfer_one_message = spi_engine_transfer_one_message;
host->prepare_message = spi_engine_prepare_message;
--
2.42.0
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