spi: mt7621-spi: remove data cache and rewrite its xfer function

The mt7621 spi controller supports continuous generic half-duplex spi
transaction. There is no need to cache xfer data at all.

To achieve this goal, the OPADDR register must be used as the first data
to be sent. And follows the eight generic DIDO registers. But one thing
different between OPADDR and DIDO registers is OPADDR has a reversed byte
order.

With this patch, any amount of data can be read/written in a single xfer
function call.

Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>

diff --git a/drivers/spi/mt7621_spi.c b/drivers/spi/mt7621_spi.c
index b37f859b98210127a8fabf9a61f8c63042d9d437..716256ab59cc5ebc6052cf52fe75d7468cfc4aad 100644 (file)
--- a/drivers/spi/mt7621_spi.c
+++ b/drivers/spi/mt7621_spi.c
@@ -15,9 +15,8 @@
 #include <wait_bit.h>
 #include <linux/io.h>
 
-#define SPI_MSG_SIZE_MAX       32      /* SPI message chunk size */
-/* Enough for SPI NAND page read / write with page size 2048 bytes */
-#define SPI_MSG_SIZE_OVERALL   (2048 + 16)
+#define MT7621_RX_FIFO_LEN     32
+#define MT7621_TX_FIFO_LEN     36
 
 #define MT7621_SPI_TRANS       0x00
 #define MT7621_SPI_TRANS_START BIT(8)
@@ -39,11 +38,16 @@
 #define MASTER_RS_CLK_SEL_SHIFT        16
 #define MASTER_RS_SLAVE_SEL    GENMASK(31, 29)
 
+#define MOREBUF_CMD_CNT                GENMASK(29, 24)
+#define MOREBUF_CMD_CNT_SHIFT  24
+#define MOREBUF_MISO_CNT       GENMASK(20, 12)
+#define MOREBUF_MISO_CNT_SHIFT 12
+#define MOREBUF_MOSI_CNT       GENMASK(8, 0)
+#define MOREBUF_MOSI_CNT_SHIFT 0
+
 struct mt7621_spi {
        void __iomem *base;
        unsigned int sys_freq;
-       u32 data[(SPI_MSG_SIZE_OVERALL / 4) + 1];
-       int tx_len;
 };
 
 static void mt7621_spi_reset(struct mt7621_spi *rs, int duplex)
@@ -129,20 +133,89 @@ static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs)
        return ret;
 }
 
+static int mt7621_spi_read(struct mt7621_spi *rs, u8 *buf, size_t len)
+{
+       size_t rx_len;
+       int i, ret;
+       u32 val = 0;
+
+       while (len) {
+               rx_len = min_t(size_t, len, MT7621_RX_FIFO_LEN);
+
+               iowrite32((rx_len * 8) << MOREBUF_MISO_CNT_SHIFT,
+                         rs->base + MT7621_SPI_MOREBUF);
+               iowrite32(MT7621_SPI_TRANS_START, rs->base + MT7621_SPI_TRANS);
+
+               ret = mt7621_spi_wait_till_ready(rs);
+               if (ret)
+                       return ret;
+
+               for (i = 0; i < rx_len; i++) {
+                       if ((i % 4) == 0)
+                               val = ioread32(rs->base + MT7621_SPI_DATA0 + i);
+                       *buf++ = val & 0xff;
+                       val >>= 8;
+               }
+
+               len -= rx_len;
+       }
+
+       return ret;
+}
+
+static int mt7621_spi_write(struct mt7621_spi *rs, const u8 *buf, size_t len)
+{
+       size_t tx_len, opcode_len, dido_len;
+       int i, ret;
+       u32 val;
+
+       while (len) {
+               tx_len = min_t(size_t, len, MT7621_TX_FIFO_LEN);
+
+               opcode_len = min_t(size_t, tx_len, 4);
+               dido_len = tx_len - opcode_len;
+
+               val = 0;
+               for (i = 0; i < opcode_len; i++) {
+                       val <<= 8;
+                       val |= *buf++;
+               }
+
+               iowrite32(val, rs->base + MT7621_SPI_OPCODE);
+
+               val = 0;
+               for (i = 0; i < dido_len; i++) {
+                       val |= (*buf++) << ((i % 4) * 8);
+
+                       if ((i % 4 == 3) || (i == dido_len - 1)) {
+                               iowrite32(val, rs->base + MT7621_SPI_DATA0 +
+                                         (i & ~3));
+                               val = 0;
+                       }
+               }
+
+               iowrite32(((opcode_len * 8) << MOREBUF_CMD_CNT_SHIFT) |
+                         ((dido_len * 8) << MOREBUF_MOSI_CNT_SHIFT),
+                         rs->base + MT7621_SPI_MOREBUF);
+               iowrite32(MT7621_SPI_TRANS_START, rs->base + MT7621_SPI_TRANS);
+
+               ret = mt7621_spi_wait_till_ready(rs);
+               if (ret)
+                       return ret;
+
+               len -= tx_len;
+       }
+
+       return 0;
+}
+
 static int mt7621_spi_xfer(struct udevice *dev, unsigned int bitlen,
                           const void *dout, void *din, unsigned long flags)
 {
        struct udevice *bus = dev->parent;
        struct mt7621_spi *rs = dev_get_priv(bus);
-       const u8 *tx_buf = dout;
-       u8 *ptr = (u8 *)dout;
-       u8 *rx_buf = din;
        int total_size = bitlen >> 3;
-       int chunk_size;
-       int rx_len = 0;
-       u32 data[(SPI_MSG_SIZE_MAX / 4) + 1] = { 0 };
-       u32 val;
-       int i;
+       int ret = 0;
 
        debug("%s: dout=%p, din=%p, len=%x, flags=%lx\n", __func__, dout, din,
              total_size, flags);
@@ -156,13 +229,6 @@ static int mt7621_spi_xfer(struct udevice *dev, unsigned int bitlen,
                return -EIO;
        }
 
-       if (dout) {
-               debug("TX-DATA: ");
-               for (i = 0; i < total_size; i++)
-                       debug("%02x ", *ptr++);
-               debug("\n");
-       }
-
        mt7621_spi_wait_till_ready(rs);
 
        /*
@@ -172,96 +238,15 @@ static int mt7621_spi_xfer(struct udevice *dev, unsigned int bitlen,
        if (flags & SPI_XFER_BEGIN)
                mt7621_spi_set_cs(rs, spi_chip_select(dev), 1);
 
-       while (total_size > 0) {
-               /* Don't exceed the max xfer size */
-               chunk_size = min_t(int, total_size, SPI_MSG_SIZE_MAX);
-
-               /*
-                * We might have some TX data buffered from the last xfer
-                * message. Make sure, that this does not exceed the max
-                * xfer size
-                */
-               if (rs->tx_len > 4)
-                       chunk_size -= rs->tx_len;
-               if (din)
-                       rx_len = chunk_size;
-
-               if (tx_buf) {
-                       /* Check if this message does not exceed the buffer */
-                       if ((chunk_size + rs->tx_len) > SPI_MSG_SIZE_OVERALL) {
-                               printf("TX message size too big (%d)\n",
-                                      chunk_size + rs->tx_len);
-                               return -EMSGSIZE;
-                       }
-
-                       /*
-                        * Write all TX data into internal buffer to collect
-                        * all TX messages into one buffer (might be split into
-                        * multiple calls to this function)
-                        */
-                       for (i = 0; i < chunk_size; i++, rs->tx_len++) {
-                               rs->data[rs->tx_len / 4] |=
-                                       tx_buf[i] << (8 * (rs->tx_len & 3));
-                       }
-               }
-
-               if (flags & SPI_XFER_END) {
-                       /* Write TX data into controller */
-                       if (rs->tx_len) {
-                               rs->data[0] = swab32(rs->data[0]);
-                               if (rs->tx_len < 4)
-                                       rs->data[0] >>= (4 - rs->tx_len) * 8;
-
-                               for (i = 0; i < rs->tx_len; i += 4) {
-                                       iowrite32(rs->data[i / 4], rs->base +
-                                                 MT7621_SPI_OPCODE + i);
-                               }
-                       }
-
-                       /* Write length into controller */
-                       val = (min_t(int, rs->tx_len, 4) * 8) << 24;
-                       if (rs->tx_len > 4)
-                               val |= (rs->tx_len - 4) * 8;
-                       val |= (rx_len * 8) << 12;
-                       iowrite32(val, rs->base + MT7621_SPI_MOREBUF);
-
-                       /* Start the xfer */
-                       setbits_le32(rs->base + MT7621_SPI_TRANS,
-                                    MT7621_SPI_TRANS_START);
-
-                       /* Wait until xfer is finished on bus */
-                       mt7621_spi_wait_till_ready(rs);
-
-                       /* Reset TX length and TX buffer for next xfer */
-                       rs->tx_len = 0;
-                       memset(rs->data, 0, sizeof(rs->data));
-               }
-
-               for (i = 0; i < rx_len; i += 4)
-                       data[i / 4] = ioread32(rs->base + MT7621_SPI_DATA0 + i);
-
-               if (rx_len) {
-                       debug("RX-DATA: ");
-                       for (i = 0; i < rx_len; i++) {
-                               rx_buf[i] = data[i / 4] >> (8 * (i & 3));
-                               debug("%02x ", rx_buf[i]);
-                       }
-                       debug("\n");
-               }
-
-               if (tx_buf)
-                       tx_buf += chunk_size;
-               if (rx_buf)
-                       rx_buf += chunk_size;
-               total_size -= chunk_size;
-       }
+       if (din)
+               ret = mt7621_spi_read(rs, din, total_size);
+       else if (dout)
+               ret = mt7621_spi_write(rs, dout, total_size);
 
-       /* Wait until xfer is finished on bus and de-assert CS */
-       mt7621_spi_wait_till_ready(rs);
        if (flags & SPI_XFER_END)
                mt7621_spi_set_cs(rs, spi_chip_select(dev), 0);
 
-       return 0;
+       return ret;
 }
 
 static int mt7621_spi_probe(struct udevice *dev)