5 files changed, 390 insertions, 14 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index d7c1741c4c5b..6fa595e0c989 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -219,6 +219,17 @@ config SPI_S3C24XX
         help
           SPI driver for Samsung S3C24XX series ARM SoCs
 
+config SPI_S3C24XX_FIQ
+        bool "S3C24XX driver with FIQ pseudo-DMA"
+        depends on SPI_S3C24XX
+        select FIQ
+        help
+          Enable FIQ support for the S3C24XX SPI driver to provide pseudo
+          DMA by using the fast-interrupt request framework, This allows
+          the driver to get DMA-like performance when there are either
+          no free DMA channels, or when doing transfers that required both
+          TX and RX data paths.
+
 config SPI_S3C24XX_GPIO
         tristate "Samsung S3C24XX series SPI by GPIO"
         depends on ARCH_S3C2410 && EXPERIMENTAL
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index a909e39f7e7c..33faa7fa0ab8 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -32,7 +32,7 @@ obj-$(CONFIG_SPI_MPC52xx)		+= mpc52xx_spi.o
 obj-$(CONFIG_SPI_MPC8xxx)               += spi_mpc8xxx.o
 obj-$(CONFIG_SPI_PPC4xx)                += spi_ppc4xx.o
 obj-$(CONFIG_SPI_S3C24XX_GPIO)          += spi_s3c24xx_gpio.o
-obj-$(CONFIG_SPI_S3C24XX)               += spi_s3c24xx.o
+obj-$(CONFIG_SPI_S3C24XX)               += spi_s3c24xx_hw.o
 obj-$(CONFIG_SPI_TXX9)                  += spi_txx9.o
 obj-$(CONFIG_SPI_XILINX)                += xilinx_spi.o
 obj-$(CONFIG_SPI_XILINX_OF)             += xilinx_spi_of.o
@@ -41,6 +41,11 @@ obj-$(CONFIG_SPI_SH_SCI)		+= spi_sh_sci.o
 obj-$(CONFIG_SPI_SH_MSIOF)              += spi_sh_msiof.o
 obj-$(CONFIG_SPI_STMP3XXX)              += spi_stmp.o
 obj-$(CONFIG_SPI_NUC900)                += spi_nuc900.o
+
+# special build for s3c24xx spi driver with fiq support
+spi_s3c24xx_hw-y                        := spi_s3c24xx.o
+spi_s3c24xx_hw-$(CONFIG_SPI_S3C24XX_FIQ) += spi_s3c24xx_fiq.o
+
 #       ... add above this line ...
 
 # SPI protocol drivers (device/link on bus)
diff --git a/drivers/spi/spi_s3c24xx.c b/drivers/spi/spi_s3c24xx.c
index 33d94f76b9ef..4b0d25b497ac 100644
--- a/drivers/spi/spi_s3c24xx.c
+++ b/drivers/spi/spi_s3c24xx.c
@@ -1,7 +1,7 @@
 /* linux/drivers/spi/spi_s3c24xx.c
  *
  * Copyright (c) 2006 Ben Dooks
- * Copyright (c) 2006 Simtec Electronics
+ * Copyright 2006-2009 Simtec Electronics
  *      Ben Dooks <ben@simtec.co.uk>
  *
  * This program is free software; you can redistribute it and/or modify
@@ -28,6 +28,11 @@
 #include <plat/regs-spi.h>
 #include <mach/spi.h>
 
+#include <plat/fiq.h>
+#include <asm/fiq.h>
+
+#include "spi_s3c24xx_fiq.h"
+
 /**
  * s3c24xx_spi_devstate - per device data
  * @hz: Last frequency calculated for @sppre field.
@@ -42,6 +47,13 @@ struct s3c24xx_spi_devstate {
         u8              sppre;
 };
 
+enum spi_fiq_mode {
+        FIQ_MODE_NONE   = 0,
+        FIQ_MODE_TX     = 1,
+        FIQ_MODE_RX     = 2,
+        FIQ_MODE_TXRX   = 3,
+};
+
 struct s3c24xx_spi {
         /* bitbang has to be first */
         struct spi_bitbang       bitbang;
@@ -52,6 +64,11 @@ struct s3c24xx_spi {
         int                      len;
         int                      count;
 
+        struct fiq_handler       fiq_handler;
+        enum spi_fiq_mode        fiq_mode;
+        unsigned char            fiq_inuse;
+        unsigned char            fiq_claimed;
+
         void                    (*set_cs)(struct s3c2410_spi_info *spi,
                                           int cs, int pol);
 
@@ -67,6 +84,7 @@ struct s3c24xx_spi {
         struct s3c2410_spi_info *pdata;
 };
 
+
 #define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT)
 #define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)
 
@@ -127,7 +145,7 @@ static int s3c24xx_spi_update_state(struct spi_device *spi,
         }
 
         if (spi->mode != cs->mode) {
-                u8 spcon = SPCON_DEFAULT;
+                u8 spcon = SPCON_DEFAULT | S3C2410_SPCON_ENSCK;
 
                 if (spi->mode & SPI_CPHA)
                         spcon |= S3C2410_SPCON_CPHA_FMTB;
@@ -214,13 +232,196 @@ static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
         return hw->tx ? hw->tx[count] : 0;
 }
 
+#ifdef CONFIG_SPI_S3C24XX_FIQ
+/* Support for FIQ based pseudo-DMA to improve the transfer speed.
+ *
+ * This code uses the assembly helper in spi_s3c24xx_spi.S which is
+ * used by the FIQ core to move data between main memory and the peripheral
+ * block. Since this is code running on the processor, there is no problem
+ * with cache coherency of the buffers, so we can use any buffer we like.
+ */
+
+/**
+ * struct spi_fiq_code - FIQ code and header
+ * @length: The length of the code fragment, excluding this header.
+ * @ack_offset: The offset from @data to the word to place the IRQ ACK bit at.
+ * @data: The code itself to install as a FIQ handler.
+ */
+struct spi_fiq_code {
+        u32     length;
+        u32     ack_offset;
+        u8      data[0];
+};
+
+extern struct spi_fiq_code s3c24xx_spi_fiq_txrx;
+extern struct spi_fiq_code s3c24xx_spi_fiq_tx;
+extern struct spi_fiq_code s3c24xx_spi_fiq_rx;
+
+/**
+ * ack_bit - turn IRQ into IRQ acknowledgement bit
+ * @irq: The interrupt number
+ *
+ * Returns the bit to write to the interrupt acknowledge register.
+ */
+static inline u32 ack_bit(unsigned int irq)
+{
+        return 1 << (irq - IRQ_EINT0);
+}
+
+/**
+ * s3c24xx_spi_tryfiq - attempt to claim and setup FIQ for transfer
+ * @hw: The hardware state.
+ *
+ * Claim the FIQ handler (only one can be active at any one time) and
+ * then setup the correct transfer code for this transfer.
+ *
+ * This call updates all the necessary state information if sucessful,
+ * so the caller does not need to do anything more than start the transfer
+ * as normal, since the IRQ will have been re-routed to the FIQ handler.
+*/
+void s3c24xx_spi_tryfiq(struct s3c24xx_spi *hw)
+{
+        struct pt_regs regs;
+        enum spi_fiq_mode mode;
+        struct spi_fiq_code *code;
+        int ret;
+
+        if (!hw->fiq_claimed) {
+                /* try and claim fiq if we haven't got it, and if not
+                 * then return and simply use another transfer method */
+
+                ret = claim_fiq(&hw->fiq_handler);
+                if (ret)
+                        return;
+        }
+
+        if (hw->tx && !hw->rx)
+                mode = FIQ_MODE_TX;
+        else if (hw->rx && !hw->tx)
+                mode = FIQ_MODE_RX;
+        else
+                mode = FIQ_MODE_TXRX;
+
+        regs.uregs[fiq_rspi] = (long)hw->regs;
+        regs.uregs[fiq_rrx]  = (long)hw->rx;
+        regs.uregs[fiq_rtx]  = (long)hw->tx + 1;
+        regs.uregs[fiq_rcount] = hw->len - 1;
+        regs.uregs[fiq_rirq] = (long)S3C24XX_VA_IRQ;
+
+        set_fiq_regs(&regs);
+
+        if (hw->fiq_mode != mode) {
+                u32 *ack_ptr;
+
+                hw->fiq_mode = mode;
+
+                switch (mode) {
+                case FIQ_MODE_TX:
+                        code = &s3c24xx_spi_fiq_tx;
+                        break;
+                case FIQ_MODE_RX:
+                        code = &s3c24xx_spi_fiq_rx;
+                        break;
+                case FIQ_MODE_TXRX:
+                        code = &s3c24xx_spi_fiq_txrx;
+                        break;
+                default:
+                        code = NULL;
+                }
+
+                BUG_ON(!code);
+
+                ack_ptr = (u32 *)&code->data[code->ack_offset];
+                *ack_ptr = ack_bit(hw->irq);
+
+                set_fiq_handler(&code->data, code->length);
+        }
+
+        s3c24xx_set_fiq(hw->irq, true);
+
+        hw->fiq_mode = mode;
+        hw->fiq_inuse = 1;
+}
+
+/**
+ * s3c24xx_spi_fiqop - FIQ core code callback
+ * @pw: Data registered with the handler
+ * @release: Whether this is a release or a return.
+ *
+ * Called by the FIQ code when another module wants to use the FIQ, so
+ * return whether we are currently using this or not and then update our
+ * internal state.
+ */
+static int s3c24xx_spi_fiqop(void *pw, int release)
+{
+        struct s3c24xx_spi *hw = pw;
+        int ret = 0;
+
+        if (release) {
+                if (hw->fiq_inuse)
+                        ret = -EBUSY;
+
+                /* note, we do not need to unroute the FIQ, as the FIQ
+                 * vector code de-routes it to signal the end of transfer */
+
+                hw->fiq_mode = FIQ_MODE_NONE;
+                hw->fiq_claimed = 0;
+        } else {
+                hw->fiq_claimed = 1;
+        }
+
+        return ret;
+}
+
+/**
+ * s3c24xx_spi_initfiq - setup the information for the FIQ core
+ * @hw: The hardware state.
+ *
+ * Setup the fiq_handler block to pass to the FIQ core.
+ */
+static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *hw)
+{
+        hw->fiq_handler.dev_id = hw;
+        hw->fiq_handler.name = dev_name(hw->dev);
+        hw->fiq_handler.fiq_op = s3c24xx_spi_fiqop;
+}
+
+/**
+ * s3c24xx_spi_usefiq - return if we should be using FIQ.
+ * @hw: The hardware state.
+ *
+ * Return true if the platform data specifies whether this channel is
+ * allowed to use the FIQ.
+ */
+static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *hw)
+{
+        return hw->pdata->use_fiq;
+}
+
+/**
+ * s3c24xx_spi_usingfiq - return if channel is using FIQ
+ * @spi: The hardware state.
+ *
+ * Return whether the channel is currently using the FIQ (separate from
+ * whether the FIQ is claimed).
+ */
+static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *spi)
+{
+        return spi->fiq_inuse;
+}
+#else
+
+static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *s) { }
+static inline void s3c24xx_spi_tryfiq(struct s3c24xx_spi *s) { }
+static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *s) { return false; }
+static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *s) { return false; }
+
+#endif /* CONFIG_SPI_S3C24XX_FIQ */
+
 static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 {
         struct s3c24xx_spi *hw = to_hw(spi);
 
-        dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
-                t->tx_buf, t->rx_buf, t->len);
-
         hw->tx = t->tx_buf;
         hw->rx = t->rx_buf;
         hw->len = t->len;
@@ -228,11 +429,14 @@ static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 
         init_completion(&hw->done);
 
+        hw->fiq_inuse = 0;
+        if (s3c24xx_spi_usefiq(hw) && t->len >= 3)
+                s3c24xx_spi_tryfiq(hw);
+
         /* send the first byte */
         writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);
 
         wait_for_completion(&hw->done);
-
         return hw->count;
 }
 
@@ -254,17 +458,27 @@ static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
                 goto irq_done;
         }
 
-        hw->count++;
+        if (!s3c24xx_spi_usingfiq(hw)) {
+                hw->count++;
 
-        if (hw->rx)
-                hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);
+                if (hw->rx)
+                        hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);
 
-        count++;
+                count++;
+
+                if (count < hw->len)
+                        writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
+                else
+                        complete(&hw->done);
+        } else {
+                hw->count = hw->len;
+                hw->fiq_inuse = 0;
+
+                if (hw->rx)
+                        hw->rx[hw->len-1] = readb(hw->regs + S3C2410_SPRDAT);
 
-        if (count < hw->len)
-                writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
-        else
                 complete(&hw->done);
+        }
 
  irq_done:
         return IRQ_HANDLED;
@@ -322,6 +536,10 @@ static int __init s3c24xx_spi_probe(struct platform_device *pdev)
         platform_set_drvdata(pdev, hw);
         init_completion(&hw->done);
 
+        /* initialise fiq handler */
+
+        s3c24xx_spi_initfiq(hw);
+
         /* setup the master state. */
 
         /* the spi->mode bits understood by this driver: */
diff --git a/drivers/spi/spi_s3c24xx_fiq.S b/drivers/spi/spi_s3c24xx_fiq.S
new file mode 100644
index 000000000000..3793cae361db
--- /dev/null
+++ b/drivers/spi/spi_s3c24xx_fiq.S
@@ -0,0 +1,116 @@
+/* linux/drivers/spi/spi_s3c24xx_fiq.S
+ *
+ * Copyright 2009 Simtec Electronics
+ *      Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C24XX SPI - FIQ pseudo-DMA transfer code
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+#include <mach/map.h>
+#include <mach/regs-irq.h>
+#include <plat/regs-spi.h>
+
+#include "spi_s3c24xx_fiq.h"
+
+        .text
+
+        @ entry to these routines is as follows, with the register names
+        @ defined in fiq.h so that they can be shared with the C files which
+        @ setup the calling registers.
+        @
+        @ fiq_rirq      The base of the IRQ registers to find S3C2410_SRCPND
+        @ fiq_rtmp      Temporary register to hold tx/rx data
+        @ fiq_rspi      The base of the SPI register block
+        @ fiq_rtx       The tx buffer pointer
+        @ fiq_rrx       The rx buffer pointer
+        @ fiq_rcount    The number of bytes to move
+
+        @ each entry starts with a word entry of how long it is
+        @ and an offset to the irq acknowledgment word
+
+ENTRY(s3c24xx_spi_fiq_rx)
+s3c24xx_spi_fix_rx:
+        .word   fiq_rx_end - fiq_rx_start
+        .word   fiq_rx_irq_ack - fiq_rx_start
+fiq_rx_start:
+        ldr     fiq_rtmp, fiq_rx_irq_ack
+        str     fiq_rtmp, [ fiq_rirq, # S3C2410_SRCPND - S3C24XX_VA_IRQ ]
+
+        ldrb    fiq_rtmp, [ fiq_rspi, #  S3C2410_SPRDAT ]
+        strb    fiq_rtmp, [ fiq_rrx ], #1
+
+        mov     fiq_rtmp, #0xff
+        strb    fiq_rtmp, [ fiq_rspi, # S3C2410_SPTDAT ]
+
+        subs    fiq_rcount, fiq_rcount, #1
+        subnes  pc, lr, #4              @@ return, still have work to do
+
+        @@ set IRQ controller so that next op will trigger IRQ
+        mov     fiq_rtmp, #0
+        str     fiq_rtmp, [ fiq_rirq, # S3C2410_INTMOD  - S3C24XX_VA_IRQ ]
+        subs    pc, lr, #4
+
+fiq_rx_irq_ack:
+        .word   0
+fiq_rx_end:
+
+ENTRY(s3c24xx_spi_fiq_txrx)
+s3c24xx_spi_fiq_txrx:
+        .word   fiq_txrx_end - fiq_txrx_start
+        .word   fiq_txrx_irq_ack - fiq_txrx_start
+fiq_txrx_start:
+
+        ldrb    fiq_rtmp, [ fiq_rspi, #  S3C2410_SPRDAT ]
+        strb    fiq_rtmp, [ fiq_rrx ], #1
+
+        ldr     fiq_rtmp, fiq_txrx_irq_ack
+        str     fiq_rtmp, [ fiq_rirq, # S3C2410_SRCPND - S3C24XX_VA_IRQ ]
+
+        ldrb    fiq_rtmp, [ fiq_rtx ], #1
+        strb    fiq_rtmp, [ fiq_rspi, # S3C2410_SPTDAT ]
+
+        subs    fiq_rcount, fiq_rcount, #1
+        subnes  pc, lr, #4              @@ return, still have work to do
+
+        mov     fiq_rtmp, #0
+        str     fiq_rtmp, [ fiq_rirq, # S3C2410_INTMOD  - S3C24XX_VA_IRQ ]
+        subs    pc, lr, #4
+
+fiq_txrx_irq_ack:
+        .word   0
+
+fiq_txrx_end:
+
+ENTRY(s3c24xx_spi_fiq_tx)
+s3c24xx_spi_fix_tx:
+        .word   fiq_tx_end - fiq_tx_start
+        .word   fiq_tx_irq_ack - fiq_tx_start
+fiq_tx_start:
+        ldrb    fiq_rtmp, [ fiq_rspi, #  S3C2410_SPRDAT ]
+
+        ldr     fiq_rtmp, fiq_tx_irq_ack
+        str     fiq_rtmp, [ fiq_rirq, # S3C2410_SRCPND - S3C24XX_VA_IRQ ]
+
+        ldrb    fiq_rtmp, [ fiq_rtx ], #1
+        strb    fiq_rtmp, [ fiq_rspi, # S3C2410_SPTDAT ]
+
+        subs    fiq_rcount, fiq_rcount, #1
+        subnes  pc, lr, #4              @@ return, still have work to do
+
+        mov     fiq_rtmp, #0
+        str     fiq_rtmp, [ fiq_rirq, # S3C2410_INTMOD  - S3C24XX_VA_IRQ ]
+        subs    pc, lr, #4
+
+fiq_tx_irq_ack:
+        .word   0
+
+fiq_tx_end:
+
+        .end
diff --git a/drivers/spi/spi_s3c24xx_fiq.h b/drivers/spi/spi_s3c24xx_fiq.h
new file mode 100644
index 000000000000..a5950bb25b51
--- /dev/null
+++ b/drivers/spi/spi_s3c24xx_fiq.h
@@ -0,0 +1,26 @@
+/* linux/drivers/spi/spi_s3c24xx_fiq.h
+ *
+ * Copyright 2009 Simtec Electronics
+ *      Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C24XX SPI - FIQ pseudo-DMA transfer support
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+/* We have R8 through R13 to play with */
+
+#ifdef __ASSEMBLY__
+#define __REG_NR(x)     r##x
+#else
+#define __REG_NR(x)     (x)
+#endif
+
+#define fiq_rspi        __REG_NR(8)
+#define fiq_rtmp        __REG_NR(9)
+#define fiq_rrx         __REG_NR(10)
+#define fiq_rtx         __REG_NR(11)
+#define fiq_rcount      __REG_NR(12)
+#define fiq_rirq        __REG_NR(13)