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[PATCH V2 1/2] SPI: MIPS: lantiq: add FALC-ON spi driver

To: Ralf Baechle <ralf@linux-mips.org>
Subject: [PATCH V2 1/2] SPI: MIPS: lantiq: add FALC-ON spi driver
From: John Crispin <blogic@openwrt.org>
Date: Fri, 9 Dec 2011 15:17:02 +0100
Cc: Wolfram Sang <w.sang@pengutronix.de>, linux-mips@linux-mips.org, John Crispin <blogic@openwrt.org>, Thomas Langer <thomas.langer@lantiq.com>, spi-devel-general@lists.sourceforge.net
Sender: linux-mips-bounce@linux-mips.org
The external bus unit (EBU) found on the FALC-ON SoC has spi emulation that is
designed for serial flash access. This driver has only been tested with m25p80
type chips. The hardware has no support for other types of spi peripherals.

Signed-off-by: Thomas Langer <thomas.langer@lantiq.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: spi-devel-general@lists.sourceforge.net

---
These 2 patches should go upstream via the MIPS tree

Changes in V2
* remove several superflous calls to dev_dbg
* make use of module_platform_driver
* remove falcon_spi_cleanup as it was an empty function
* return real error codes instead of -1
* fixes operator spacing errors
* split arch and driver specific patches
* squash some lines to make use of the full 80 available chars
* Kconfig is now alphabetic again
* replace BUG() with WARN_ON()

 drivers/spi/Kconfig      |    9 +
 drivers/spi/Makefile     |    1 +
 drivers/spi/spi-falcon.c |  445 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 455 insertions(+), 0 deletions(-)
 create mode 100644 drivers/spi/spi-falcon.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index a1fd73d..e5ce95d 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -138,6 +138,15 @@ config SPI_EP93XX
          This enables using the Cirrus EP93xx SPI controller in master
          mode.
 
+config SPI_FALCON
+       tristate "Falcon SPI controller support"
+       depends on SOC_FALCON
+       help
+         The external bus unit (EBU) found on the FALC-ON SoC has SPI
+         emulation that is designed for serial flash access. This driver
+         has only been tested with m25p80 type chips. The hardware has no
+         support for other types of spi peripherals.
+
 config SPI_GPIO
        tristate "GPIO-based bitbanging SPI Master"
        depends on GENERIC_GPIO
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 61c3261..570894c 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_SPI_DW_MMIO)             += spi-dw-mmio.o
 obj-$(CONFIG_SPI_DW_PCI)               += spi-dw-midpci.o
 spi-dw-midpci-objs                     := spi-dw-pci.o spi-dw-mid.o
 obj-$(CONFIG_SPI_EP93XX)               += spi-ep93xx.o
+obj-$(CONFIG_SPI_FALCON)               += spi-falcon.o
 obj-$(CONFIG_SPI_FSL_LIB)              += spi-fsl-lib.o
 obj-$(CONFIG_SPI_FSL_ESPI)             += spi-fsl-espi.o
 obj-$(CONFIG_SPI_FSL_SPI)              += spi-fsl-spi.o
diff --git a/drivers/spi/spi-falcon.c b/drivers/spi/spi-falcon.c
new file mode 100644
index 0000000..7aa044d
--- /dev/null
+++ b/drivers/spi/spi-falcon.c
@@ -0,0 +1,445 @@
+/*
+ *  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.
+ *
+ *  Copyright (C) 2010 Thomas Langer <thomas.langer@lantiq.com>
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/delay.h>
+#include <linux/workqueue.h>
+
+#include <lantiq_soc.h>
+
+#define DRV_NAME                       "falcon_spi"
+
+#define FALCON_SPI_XFER_BEGIN          (1 << 0)
+#define FALCON_SPI_XFER_END            (1 << 1)
+
+/* Bus Read Configuration Register0 */
+#define LTQ_BUSRCON0   0x00000010
+/* Bus Write Configuration Register0 */
+#define LTQ_BUSWCON0   0x00000018
+/* Serial Flash Configuration Register */
+#define LTQ_SFCON      0x00000080
+/* Serial Flash Time Register */
+#define LTQ_SFTIME     0x00000084
+/* Serial Flash Status Register */
+#define LTQ_SFSTAT     0x00000088
+/* Serial Flash Command Register */
+#define LTQ_SFCMD      0x0000008C
+/* Serial Flash Address Register */
+#define LTQ_SFADDR     0x00000090
+/* Serial Flash Data Register */
+#define LTQ_SFDATA     0x00000094
+/* Serial Flash I/O Control Register */
+#define LTQ_SFIO       0x00000098
+/* EBU Clock Control Register */
+#define LTQ_EBUCC      0x000000C4
+
+/* Dummy Phase Length */
+#define SFCMD_DUMLEN_OFFSET    16
+#define SFCMD_DUMLEN_MASK      0x000F0000
+/* Chip Select */
+#define SFCMD_CS_OFFSET                24
+#define SFCMD_CS_MASK          0x07000000
+/* field offset */
+#define SFCMD_ALEN_OFFSET      20
+#define SFCMD_ALEN_MASK                0x00700000
+/* SCK Rise-edge Position */
+#define SFTIME_SCKR_POS_OFFSET 8
+#define SFTIME_SCKR_POS_MASK   0x00000F00
+/* SCK Period */
+#define SFTIME_SCK_PER_OFFSET  0
+#define SFTIME_SCK_PER_MASK    0x0000000F
+/* SCK Fall-edge Position */
+#define SFTIME_SCKF_POS_OFFSET 12
+#define SFTIME_SCKF_POS_MASK   0x0000F000
+/* Device Size */
+#define SFCON_DEV_SIZE_A23_0   0x03000000
+#define SFCON_DEV_SIZE_MASK    0x0F000000
+/* Read Data Position */
+#define SFTIME_RD_POS_MASK     0x000F0000
+/* Data Output */
+#define SFIO_UNUSED_WD_MASK    0x0000000F
+/* Command Opcode mask */
+#define SFCMD_OPC_MASK         0x000000FF
+/* dlen bytes of data to write */
+#define SFCMD_DIR_WRITE                0x00000100
+/* Data Length offset */
+#define SFCMD_DLEN_OFFSET      9
+/* Command Error */
+#define SFSTAT_CMD_ERR         0x20000000
+/* Access Command Pending */
+#define SFSTAT_CMD_PEND                0x00400000
+/* Frequency set to 100MHz. */
+#define EBUCC_EBUDIV_SELF100   0x00000001
+/* Serial Flash */
+#define BUSRCON0_AGEN_SERIAL_FLASH     0xF0000000
+/* 8-bit multiplexed */
+#define BUSRCON0_PORTW_8_BIT_MUX       0x00000000
+/* Serial Flash */
+#define BUSWCON0_AGEN_SERIAL_FLASH     0xF0000000
+/* Chip Select after opcode */
+#define SFCMD_KEEP_CS_KEEP_SELECTED    0x00008000
+
+struct falcon_spi {
+       u32 sfcmd; /* for caching of opcode, direction, ... */
+       struct spi_master *master;
+};
+
+int
+falcon_spi_xfer(struct spi_device *spi, struct spi_transfer *t,
+               unsigned long flags)
+{
+       struct device *dev = &spi->dev;
+       struct falcon_spi *priv = spi_master_get_devdata(spi->master);
+       const u8 *txp = t->tx_buf;
+       u8 *rxp = t->rx_buf;
+       unsigned int bytelen = ((8 * t->len + 7) / 8);
+       unsigned int len, alen, dumlen;
+       u32 val;
+       enum {
+               state_init,
+               state_command_prepare,
+               state_write,
+               state_read,
+               state_disable_cs,
+               state_end
+       } state = state_init;
+
+       do {
+               switch (state) {
+               case state_init: /* detect phase of upper layer sequence */
+               {
+                       /* initial write ? */
+                       if (flags & FALCON_SPI_XFER_BEGIN) {
+                               if (!txp) {
+                                       dev_err(dev,
+                                               "BEGIN without tx data!\n");
+                                       return -ENODATA;
+                               }
+                               /*
+                                * Prepare the parts of the sfcmd register,
+                                * which should not change during a sequence!
+                                * Only exception are the length fields,
+                                * especially alen and dumlen.
+                                */
+
+                               priv->sfcmd = ((spi->chip_select
+                                               << SFCMD_CS_OFFSET)
+                                              & SFCMD_CS_MASK);
+                               priv->sfcmd |= SFCMD_KEEP_CS_KEEP_SELECTED;
+                               priv->sfcmd |= *txp;
+                               txp++;
+                               bytelen--;
+                               if (bytelen) {
+                                       /*
+                                        * more data:
+                                        * maybe address and/or dummy
+                                        */
+                                       state = state_command_prepare;
+                                       break;
+                               } else {
+                                       dev_dbg(dev, "write cmd %02X\n",
+                                               priv->sfcmd & SFCMD_OPC_MASK);
+                               }
+                       }
+                       /* continued write ? */
+                       if (txp && bytelen) {
+                               state = state_write;
+                               break;
+                       }
+                       /* read data? */
+                       if (rxp && bytelen) {
+                               state = state_read;
+                               break;
+                       }
+                       /* end of sequence? */
+                       if (flags & FALCON_SPI_XFER_END)
+                               state = state_disable_cs;
+                       else
+                               state = state_end;
+                       break;
+               }
+               /* collect tx data for address and dummy phase */
+               case state_command_prepare:
+               {
+                       /* txp is valid, already checked */
+                       val = 0;
+                       alen = 0;
+                       dumlen = 0;
+                       while (bytelen > 0) {
+                               if (alen < 3) {
+                                       val = (val << 8) | (*txp++);
+                                       alen++;
+                               } else if ((dumlen < 15) && (*txp == 0)) {
+                                       /*
+                                        * assume dummy bytes are set to 0
+                                        * from upper layer
+                                        */
+                                       dumlen++;
+                                       txp++;
+                               } else
+                                       break;
+                               bytelen--;
+                       }
+                       priv->sfcmd &= ~(SFCMD_ALEN_MASK | SFCMD_DUMLEN_MASK);
+                       priv->sfcmd |= (alen << SFCMD_ALEN_OFFSET) |
+                                        (dumlen << SFCMD_DUMLEN_OFFSET);
+                       if (alen > 0)
+                               ltq_ebu_w32(val, LTQ_SFADDR);
+
+                       dev_dbg(dev, "write cmd %02X, alen=%d "
+                               "(addr=%06X) dumlen=%d\n",
+                               priv->sfcmd & SFCMD_OPC_MASK,
+                               alen, val, dumlen);
+
+                       if (bytelen > 0) {
+                               /* continue with write */
+                               state = state_write;
+                       } else if (flags & FALCON_SPI_XFER_END) {
+                               /* end of sequence? */
+                               state = state_disable_cs;
+                       } else {
+                               /*
+                                * go to end and expect another
+                                * call (read or write)
+                                */
+                               state = state_end;
+                       }
+                       break;
+               }
+               case state_write:
+               {
+                       /* txp still valid */
+                       priv->sfcmd |= SFCMD_DIR_WRITE;
+                       len = 0;
+                       val = 0;
+                       do {
+                               if (bytelen--)
+                                       val |= (*txp++) << (8 * len++);
+                               if ((flags & FALCON_SPI_XFER_END)
+                                   && (bytelen == 0)) {
+                                       priv->sfcmd &=
+                                               ~SFCMD_KEEP_CS_KEEP_SELECTED;
+                               }
+                               if ((len == 4) || (bytelen == 0)) {
+                                       ltq_ebu_w32(val, LTQ_SFDATA);
+                                       ltq_ebu_w32(priv->sfcmd
+                                               | (len<<SFCMD_DLEN_OFFSET),
+                                               LTQ_SFCMD);
+                                       len = 0;
+                                       val = 0;
+                                       priv->sfcmd &= ~(SFCMD_ALEN_MASK
+                                                        | SFCMD_DUMLEN_MASK);
+                               }
+                       } while (bytelen);
+                       state = state_end;
+                       break;
+               }
+               case state_read:
+               {
+                       /* read data */
+                       priv->sfcmd &= ~SFCMD_DIR_WRITE;
+                       do {
+                               if ((flags & FALCON_SPI_XFER_END)
+                                   && (bytelen <= 4)) {
+                                       priv->sfcmd &=
+                                               ~SFCMD_KEEP_CS_KEEP_SELECTED;
+                               }
+                               len = (bytelen > 4) ? 4 : bytelen;
+                               bytelen -= len;
+                               ltq_ebu_w32(priv->sfcmd
+                                       |(len<<SFCMD_DLEN_OFFSET), LTQ_SFCMD);
+                               priv->sfcmd &= ~(SFCMD_ALEN_MASK
+                                                | SFCMD_DUMLEN_MASK);
+                               do {
+                                       val = ltq_ebu_r32(LTQ_SFSTAT);
+                                       if (val & SFSTAT_CMD_ERR) {
+                                               /* reset error status */
+                                               dev_err(dev, "SFSTAT: CMD_ERR "
+                                                       "(%x)\n", val);
+                                               ltq_ebu_w32(SFSTAT_CMD_ERR,
+                                                       LTQ_SFSTAT);
+                                               return -EBADE;
+                                       }
+                               } while (val & SFSTAT_CMD_PEND);
+                               val = ltq_ebu_r32(LTQ_SFDATA);
+                               do {
+                                       *rxp = (val & 0xFF);
+                                       rxp++;
+                                       val >>= 8;
+                                       len--;
+                               } while (len);
+                       } while (bytelen);
+                       state = state_end;
+                       break;
+               }
+               case state_disable_cs:
+               {
+                       priv->sfcmd &= ~SFCMD_KEEP_CS_KEEP_SELECTED;
+                       ltq_ebu_w32(priv->sfcmd | (0 << SFCMD_DLEN_OFFSET),
+                               LTQ_SFCMD);
+                       val = ltq_ebu_r32(LTQ_SFSTAT);
+                       if (val & SFSTAT_CMD_ERR) {
+                               /* reset error status */
+                               dev_err(dev, "SFSTAT: CMD_ERR (%x)\n", val);
+                               ltq_ebu_w32(SFSTAT_CMD_ERR, LTQ_SFSTAT);
+                               return -EBADE;
+                       }
+                       state = state_end;
+                       break;
+               }
+               case state_end:
+                       break;
+               }
+       } while (state != state_end);
+
+       return 0;
+}
+
+static int
+falcon_spi_setup(struct spi_device *spi)
+{
+       const u32 ebuclk = CLOCK_100M;
+       unsigned int i;
+       unsigned long flags;
+
+       if (spi->master->bus_num > 0 || spi->chip_select > 0)
+               return -ENODEV;
+
+       spin_lock_irqsave(&ebu_lock, flags);
+
+       if (ebuclk < spi->max_speed_hz) {
+               /* set EBU clock to 100 MHz */
+               ltq_sys1_w32_mask(0, EBUCC_EBUDIV_SELF100, LTQ_EBUCC);
+               i = 1; /* divider */
+       } else {
+               /* set EBU clock to 50 MHz */
+               ltq_sys1_w32_mask(EBUCC_EBUDIV_SELF100, 0, LTQ_EBUCC);
+
+               /* search for suitable divider */
+               for (i = 1; i < 7; i++) {
+                       if (ebuclk / i <= spi->max_speed_hz)
+                               break;
+               }
+       }
+
+       /* setup period of serial clock */
+       ltq_ebu_w32_mask(SFTIME_SCKF_POS_MASK
+                    | SFTIME_SCKR_POS_MASK
+                    | SFTIME_SCK_PER_MASK,
+                    (i << SFTIME_SCKR_POS_OFFSET)
+                    | (i << (SFTIME_SCK_PER_OFFSET + 1)),
+                    LTQ_SFTIME);
+
+       /*
+        * set some bits of unused_wd, to not trigger HOLD/WP
+        * signals on non QUAD flashes
+        */
+       ltq_ebu_w32((SFIO_UNUSED_WD_MASK & (0x8 | 0x4)), LTQ_SFIO);
+
+       ltq_ebu_w32(BUSRCON0_AGEN_SERIAL_FLASH | BUSRCON0_PORTW_8_BIT_MUX,
+               LTQ_BUSRCON0);
+       ltq_ebu_w32(BUSWCON0_AGEN_SERIAL_FLASH, LTQ_BUSWCON0);
+       /* set address wrap around to maximum for 24-bit addresses */
+       ltq_ebu_w32_mask(SFCON_DEV_SIZE_MASK, SFCON_DEV_SIZE_A23_0, LTQ_SFCON);
+
+       spin_unlock_irqrestore(&ebu_lock, flags);
+
+       return 0;
+}
+
+static int
+falcon_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
+       struct falcon_spi *priv = spi_master_get_devdata(spi->master);
+       struct spi_transfer *t;
+       unsigned long spi_flags;
+       unsigned long flags;
+       int ret = 0;
+
+       priv->sfcmd = 0;
+       m->actual_length = 0;
+
+       spi_flags = FALCON_SPI_XFER_BEGIN;
+       list_for_each_entry(t, &m->transfers, transfer_list) {
+               if (list_is_last(&t->transfer_list, &m->transfers))
+                       spi_flags |= FALCON_SPI_XFER_END;
+
+               spin_lock_irqsave(&ebu_lock, flags);
+               ret = falcon_spi_xfer(spi, t, spi_flags);
+               spin_unlock_irqrestore(&ebu_lock, flags);
+
+               if (ret)
+                       break;
+
+               m->actual_length += t->len;
+
+               WARN_ON(t->delay_usecs || t->cs_change);
+               spi_flags = 0;
+       }
+
+       m->status = ret;
+       m->complete(m->context);
+
+       return 0;
+}
+
+static int __devinit
+falcon_spi_probe(struct platform_device *pdev)
+{
+       struct falcon_spi *priv;
+       struct spi_master *master;
+       int ret;
+
+       master = spi_alloc_master(&pdev->dev, sizeof(*priv));
+       if (!master)
+               return -ENOMEM;
+
+       priv = spi_master_get_devdata(master);
+       priv->master = master;
+
+       master->mode_bits = SPI_MODE_3;
+       master->num_chipselect = 1;
+       master->bus_num = 0;
+       master->setup = falcon_spi_setup;
+       master->transfer = falcon_spi_transfer;
+
+       platform_set_drvdata(pdev, priv);
+
+       ret = spi_register_master(master);
+       if (ret)
+               spi_master_put(master);
+
+       return ret;
+}
+
+static int __devexit
+falcon_spi_remove(struct platform_device *pdev)
+{
+       struct falcon_spi *priv = platform_get_drvdata(pdev);
+
+       spi_unregister_master(priv->master);
+
+       return 0;
+}
+
+static struct platform_driver falcon_spi_driver = {
+       .probe  = falcon_spi_probe,
+       .remove = __devexit_p(falcon_spi_remove),
+       .driver = {
+               .name   = DRV_NAME,
+               .owner  = THIS_MODULE
+       }
+};
+
+module_platform_driver(falcon_spi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Lantiq Falcon SPI controller driver");
-- 
1.7.7.1


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