Re: [RFC/PATCHv2 3/3] spi: dw-spi: Pointers select 16b vs. 32b DesignWare access

Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx> · Mon, 9 Mar 2015 13:01:10 -0500

On 03/07/2015 01:52 PM, Andy Shevchenko wrote:
On Sat, Mar 7, 2015 at 1:46 AM,  <tthayer@xxxxxxxxxxxxxxxxxxxxx> wrote:
From: Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx>

Altera's Arria10 SoC interconnect requires a 32 bit write for APB
peripherals. The current spi-dw driver uses 16bit accesses in
some locations. Use function pointers to support 32 bit accesses
but retain legacy 16 bit access.


Thanks for this version. My comments below.

Signed-off-by: Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx>
---
  drivers/spi/spi-dw-mmio.c |    7 ++++++-
  drivers/spi/spi-dw.c      |   29 +++++++++++++++++------------
  drivers/spi/spi-dw.h      |   12 ++++++++++++
  3 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e12..c4fe9e9 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -76,8 +76,13 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)

         num_cs = 4;

-       if (pdev->dev.of_node)
+       if (pdev->dev.of_node) {
                 of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
+               if (of_property_read_bool(pdev->dev.of_node, "32bit_access")) {
+                       dws->read_w = dw_readw32;
+                       dws->write_w = dw_writew32;

Can we use just  readw/writew (w/o underscores) as names for the accessors?


I tried this initially and got a namespace conflict with the readw & 
write2 macros.
macro writew passed 3 arguments, but takes just 2
macro readw passed 2 arguments, but takes just 1

+               }
+       }

         dws->num_cs = num_cs;

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index c5fa2be..d008791 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -157,7 +157,7 @@ static inline u32 tx_max(struct dw_spi *dws)
         u32 tx_left, tx_room, rxtx_gap;

         tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
-       tx_room = dws->fifo_len - dw_readw(dws, DW_SPI_TXFLR);
+       tx_room = dws->fifo_len - dws->read_w(dws, DW_SPI_TXFLR);

         /*
          * Another concern is about the tx/rx mismatch, we
@@ -178,7 +178,7 @@ static inline u32 rx_max(struct dw_spi *dws)
  {
         u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;

-       return min_t(u32, rx_left, dw_readw(dws, DW_SPI_RXFLR));
+       return min_t(u32, rx_left, dws->read_w(dws, DW_SPI_RXFLR));
  }

  static void dw_writer(struct dw_spi *dws)
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
                         else
                                 txw = *(u16 *)(dws->tx);
                 }
-               dw_writew(dws, DW_SPI_DR, txw);
+               dws->write_w(dws, DW_SPI_DR, txw);
                 dws->tx += dws->n_bytes;
         }
  }
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
         u16 rxw;

         while (max--) {
-               rxw = dw_readw(dws, DW_SPI_DR);
+               rxw = dws->read_w(dws, DW_SPI_DR);
                 /* Care rx only if the transfer's original "rx" is not null */
                 if (dws->rx_end - dws->len) {
                         if (dws->n_bytes == 1)
@@ -254,11 +254,11 @@ static void int_error_stop(struct dw_spi *dws, const char *msg)

  static irqreturn_t interrupt_transfer(struct dw_spi *dws)
  {
-       u16 irq_status = dw_readw(dws, DW_SPI_ISR);
+       u16 irq_status = dws->read_w(dws, DW_SPI_ISR);

         /* Error handling */
         if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
-               dw_readw(dws, DW_SPI_ICR);
+               dws->read_w(dws, DW_SPI_ICR);
                 int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
                 return IRQ_HANDLED;
         }
@@ -283,7 +283,7 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id)
  {
         struct spi_master *master = dev_id;
         struct dw_spi *dws = spi_master_get_devdata(master);
-       u16 irq_status = dw_readw(dws, DW_SPI_ISR) & 0x3f;
+       u16 irq_status = dws->read_w(dws, DW_SPI_ISR) & 0x3f;

         if (!irq_status)
                 return IRQ_NONE;
@@ -379,7 +379,7 @@ static int dw_spi_transfer_one(struct spi_master *master,
                 cr0 |= (chip->tmode << SPI_TMOD_OFFSET);
         }

-       dw_writew(dws, DW_SPI_CTRL0, cr0);
+       dws->write_w(dws, DW_SPI_CTRL0, cr0);

         /* Check if current transfer is a DMA transaction */
         dws->dma_mapped = map_dma_buffers(master, spi, transfer);
@@ -393,7 +393,7 @@ static int dw_spi_transfer_one(struct spi_master *master,
          */
         if (!dws->dma_mapped && !chip->poll_mode) {
                 txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
-               dw_writew(dws, DW_SPI_TXFLTR, txlevel);
+               dws->write_w(dws, DW_SPI_TXFLTR, txlevel);

                 /* Set the interrupt mask */
                 imask |= SPI_INT_TXEI | SPI_INT_TXOI |
@@ -516,11 +516,11 @@ static void spi_hw_init(struct device *dev, struct dw_spi *dws)
                 u32 fifo;

                 for (fifo = 1; fifo < 256; fifo++) {
-                       dw_writew(dws, DW_SPI_TXFLTR, fifo);
-                       if (fifo != dw_readw(dws, DW_SPI_TXFLTR))
+                       dws->write_w(dws, DW_SPI_TXFLTR, fifo);
+                       if (fifo != dws->read_w(dws, DW_SPI_TXFLTR))
                                 break;
                 }
-               dw_writew(dws, DW_SPI_TXFLTR, 0);
+               dws->write_w(dws, DW_SPI_TXFLTR, 0);

                 dws->fifo_len = (fifo == 1) ? 0 : fifo;
                 dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
@@ -545,6 +545,11 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
         dws->dma_addr = (dma_addr_t)(dws->paddr + 0x60);
         snprintf(dws->name, sizeof(dws->name), "dw_spi%d", dws->bus_num);

+       if (!dws->read_w)
+               dws->read_w = dw_readw;
+       if (!dws->write_w)
+               dws->write_w = dw_writew;
+
         ret = devm_request_irq(dev, dws->irq, dw_spi_irq, IRQF_SHARED,
                         dws->name, master);
         if (ret < 0) {
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 855bfdd..1df09e2 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -141,6 +141,8 @@ struct dw_spi {
  #ifdef CONFIG_DEBUG_FS
         struct dentry *debugfs;
  #endif
+       u16 (*read_w)(struct dw_spi *dws, u32 offset);
+       void (*write_w)(struct dw_spi *dws, u32 offset, u16 val);
  };

  static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
@@ -163,6 +165,16 @@ static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
         __raw_writew(val, dws->regs + offset);
  }

+static inline u16 dw_readw32(struct dw_spi *dws, u32 offset)
+{
+       return (u16)__raw_readl(dws->regs + offset);
+}
+
+static inline void dw_writew32(struct dw_spi *dws, u32 offset, u16 val)
+{
+       __raw_writel((u32)val, dws->regs + offset);
+}
+

So, does simple
dws->readw = dw_readl;
dws->writew = dw_writel;

work for you?


Yes, but I get the macro conflict shown above and "assignment from 
incompatible pointer type" warnings. If I use the dws->read_w and 
dws->write_w names, I get the incompatible pointer type warnings but it 
works.

Thanks for reviewing.

  static inline void spi_enable_chip(struct dw_spi *dws, int enable)
  {
         dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));
--
1.7.9.5

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