xilinx_spi: add support for the DS570 IP.

This patch adds in support for the DS570 IP.

It's register compatible with the DS464, but adds support for 8/16/32 SPI.

The 8/16/32 support is added by attaching callbacks reading/writing the
proper amount of data. To indicate to the driver which amount of bits
to use a new field is introduced in the platform data struct.

Acked-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: John Linn <John.Linn@xilinx.com>
Signed-off-by: Richard Röjfors <richard.rojfors@mocean-labs.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 87 insertions, 31 deletions

diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c
index 135a3a5931a4..b927812822c1 100644
--- a/drivers/spi/xilinx_spi.c
+++ b/drivers/spi/xilinx_spi.c
@@ -27,7 +27,7 @@
 /* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
  * Product Specification", DS464
  */
-#define XSPI_CR_OFFSET          0x60    /* 16-bit Control Register */
+#define XSPI_CR_OFFSET          0x60    /* Control Register */
 
 #define XSPI_CR_ENABLE          0x02
 #define XSPI_CR_MASTER_MODE     0x04
@@ -38,8 +38,9 @@
 #define XSPI_CR_RXFIFO_RESET    0x40
 #define XSPI_CR_MANUAL_SSELECT  0x80
 #define XSPI_CR_TRANS_INHIBIT   0x100
+#define XSPI_CR_LSB_FIRST       0x200
 
-#define XSPI_SR_OFFSET          0x64    /* 8-bit Status Register */
+#define XSPI_SR_OFFSET          0x64    /* Status Register */
 
 #define XSPI_SR_RX_EMPTY_MASK   0x01    /* Receive FIFO is empty */
 #define XSPI_SR_RX_FULL_MASK    0x02    /* Receive FIFO is full */
@@ -47,8 +48,8 @@
 #define XSPI_SR_TX_FULL_MASK    0x08    /* Transmit FIFO is full */
 #define XSPI_SR_MODE_FAULT_MASK 0x10    /* Mode fault error */
 
-#define XSPI_TXD_OFFSET         0x68    /* 8-bit Data Transmit Register */
-#define XSPI_RXD_OFFSET         0x6c    /* 8-bit Data Receive Register */
+#define XSPI_TXD_OFFSET         0x68    /* Data Transmit Register */
+#define XSPI_RXD_OFFSET         0x6c    /* Data Receive Register */
 
 #define XSPI_SSR_OFFSET         0x70    /* 32-bit Slave Select Register */
 
@@ -68,6 +69,7 @@
 #define XSPI_INTR_TX_UNDERRUN           0x08    /* TxFIFO was underrun */
 #define XSPI_INTR_RX_FULL               0x10    /* RxFIFO is full */
 #define XSPI_INTR_RX_OVERRUN            0x20    /* RxFIFO was overrun */
+#define XSPI_INTR_TX_HALF_EMPTY         0x40    /* TxFIFO is half empty */
 
 #define XIPIF_V123B_RESETR_OFFSET       0x40    /* IPIF reset register */
 #define XIPIF_V123B_RESET_MASK          0x0a    /* the value to write */
@@ -81,15 +83,61 @@ struct xilinx_spi {
 
         u32             irq;
 
-        u32             speed_hz; /* SCK has a fixed frequency of speed_hz Hz */
-
         u8 *rx_ptr;             /* pointer in the Tx buffer */
         const u8 *tx_ptr;       /* pointer in the Rx buffer */
         int remaining_bytes;    /* the number of bytes left to transfer */
+        u8 bits_per_word;
         unsigned int (*read_fn) (void __iomem *);
         void (*write_fn) (u32, void __iomem *);
+        void (*tx_fn) (struct xilinx_spi *);
+        void (*rx_fn) (struct xilinx_spi *);
 };
 
+static void xspi_tx8(struct xilinx_spi *xspi)
+{
+        xspi->write_fn(*xspi->tx_ptr, xspi->regs + XSPI_TXD_OFFSET);
+        xspi->tx_ptr++;
+}
+
+static void xspi_tx16(struct xilinx_spi *xspi)
+{
+        xspi->write_fn(*(u16 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
+        xspi->tx_ptr += 2;
+}
+
+static void xspi_tx32(struct xilinx_spi *xspi)
+{
+        xspi->write_fn(*(u32 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
+        xspi->tx_ptr += 4;
+}
+
+static void xspi_rx8(struct xilinx_spi *xspi)
+{
+        u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
+        if (xspi->rx_ptr) {
+                *xspi->rx_ptr = data & 0xff;
+                xspi->rx_ptr++;
+        }
+}
+
+static void xspi_rx16(struct xilinx_spi *xspi)
+{
+        u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
+        if (xspi->rx_ptr) {
+                *(u16 *)(xspi->rx_ptr) = data & 0xffff;
+                xspi->rx_ptr += 2;
+        }
+}
+
+static void xspi_rx32(struct xilinx_spi *xspi)
+{
+        u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
+        if (xspi->rx_ptr) {
+                *(u32 *)(xspi->rx_ptr) = data;
+                xspi->rx_ptr += 4;
+        }
+}
+
 static void xspi_init_hw(struct xilinx_spi *xspi)
 {
         void __iomem *regs_base = xspi->regs;
@@ -107,8 +155,8 @@ static void xspi_init_hw(struct xilinx_spi *xspi)
         /* Disable the transmitter, enable Manual Slave Select Assertion,
          * put SPI controller into master mode, and enable it */
         xspi->write_fn(XSPI_CR_TRANS_INHIBIT | XSPI_CR_MANUAL_SSELECT |
-                XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE,
-                regs_base + XSPI_CR_OFFSET);
+                XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET |
+                XSPI_CR_RXFIFO_RESET, regs_base + XSPI_CR_OFFSET);
 }
 
 static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
@@ -141,18 +189,20 @@ static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
 
 /* spi_bitbang requires custom setup_transfer() to be defined if there is a
  * custom txrx_bufs(). We have nothing to setup here as the SPI IP block
- * supports just 8 bits per word, and SPI clock can't be changed in software.
- * Check for 8 bits per word. Chip select delay calculations could be
+ * supports 8 or 16 bits per word which cannot be changed in software.
+ * SPI clock can't be changed in software either.
+ * Check for correct bits per word. Chip select delay calculations could be
  * added here as soon as bitbang_work() can be made aware of the delay value.
  */
 static int xilinx_spi_setup_transfer(struct spi_device *spi,
                 struct spi_transfer *t)
 {
+        struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
         u8 bits_per_word;
 
         bits_per_word = (t && t->bits_per_word)
                          ? t->bits_per_word : spi->bits_per_word;
-        if (bits_per_word != 8) {
+        if (bits_per_word != xspi->bits_per_word) {
                 dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
                         __func__, bits_per_word);
                 return -EINVAL;
@@ -163,17 +213,16 @@ static int xilinx_spi_setup_transfer(struct spi_device *spi,
 
 static int xilinx_spi_setup(struct spi_device *spi)
 {
-        struct spi_bitbang *bitbang;
-        struct xilinx_spi *xspi;
-        int retval;
-
-        xspi = spi_master_get_devdata(spi->master);
-        bitbang = &xspi->bitbang;
-
-        retval = xilinx_spi_setup_transfer(spi, NULL);
-        if (retval < 0)
-                return retval;
-
+        /* always return 0, we can not check the number of bits.
+         * There are cases when SPI setup is called before any driver is
+         * there, in that case the SPI core defaults to 8 bits, which we
+         * do not support in some cases. But if we return an error, the
+         * SPI device would not be registered and no driver can get hold of it
+         * When the driver is there, it will call SPI setup again with the
+         * correct number of bits per transfer.
+         * If a driver setups with the wrong bit number, it will fail when
+         * it tries to do a transfer
+         */
         return 0;
 }
 
@@ -185,11 +234,10 @@ static void xilinx_spi_fill_tx_fifo(struct xilinx_spi *xspi)
         sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
         while ((sr & XSPI_SR_TX_FULL_MASK) == 0 && xspi->remaining_bytes > 0) {
                 if (xspi->tx_ptr)
-                        xspi->write_fn(*xspi->tx_ptr++,
-                                xspi->regs + XSPI_TXD_OFFSET);
+                        xspi->tx_fn(xspi);
                 else
                         xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
-                xspi->remaining_bytes--;
+                xspi->remaining_bytes -= xspi->bits_per_word / 8;
                 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
         }
 }
@@ -260,12 +308,7 @@ static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
                 /* Read out all the data from the Rx FIFO */
                 sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
                 while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
-                        u8 data;
-
-                        data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
-                        if (xspi->rx_ptr) {
-                                *xspi->rx_ptr++ = data;
-                        }
+                        xspi->rx_fn(xspi);
                         sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
                 }
 
@@ -337,6 +380,19 @@ struct spi_master *xilinx_spi_init(struct device *dev, struct resource *mem,
                 xspi->read_fn = ioread32be;
                 xspi->write_fn = iowrite32be;
         }
+        xspi->bits_per_word = pdata->bits_per_word;
+        if (xspi->bits_per_word == 8) {
+                xspi->tx_fn = xspi_tx8;
+                xspi->rx_fn = xspi_rx8;
+        } else if (xspi->bits_per_word == 16) {
+                xspi->tx_fn = xspi_tx16;
+                xspi->rx_fn = xspi_rx16;
+        } else if (xspi->bits_per_word == 32) {
+                xspi->tx_fn = xspi_tx32;
+                xspi->rx_fn = xspi_rx32;
+        } else
+                goto unmap_io;
+
 
         /* SPI controller initializations */
         xspi_init_hw(xspi);