spi/dw_spi: add DMA support

dw_spi driver in upstream only supports PIO mode, and this patch
will support it to cowork with the Designware dma controller used
on Intel Moorestown platform, at the same time it provides a general
framework to support dw_spi core to cowork with dma controllers on
other platforms

It has been tested with a Option GTM501L 3G modem and Infenion 60x60
modem. To use DMA mode, DMA controller 2 of Moorestown has to be enabled

Also change the dma interface suggested by Linus Walleij.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
[Typo fix and renames to match intel_mid_dma renaming]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 223 insertions, 0 deletions

diff --git a/drivers/spi/dw_spi_mid.c b/drivers/spi/dw_spi_mid.c
new file mode 100644
index 000000000000..c91c966e0717
--- /dev/null
+++ b/drivers/spi/dw_spi_mid.c
@@ -0,0 +1,223 @@
+/*
+ * dw_spi_mid.c - special handling for DW core on Intel MID platform
+ *
+ * Copyright (c) 2009, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/dw_spi.h>
+
+#ifdef CONFIG_SPI_DW_MID_DMA
+#include <linux/intel_mid_dma.h>
+#include <linux/pci.h>
+
+struct mid_dma {
+        struct intel_mid_dma_slave      dmas_tx;
+        struct intel_mid_dma_slave      dmas_rx;
+};
+
+static bool mid_spi_dma_chan_filter(struct dma_chan *chan, void *param)
+{
+        struct dw_spi *dws = param;
+
+        return dws->dmac && (&dws->dmac->dev == chan->device->dev);
+}
+
+static int mid_spi_dma_init(struct dw_spi *dws)
+{
+        struct mid_dma *dw_dma = dws->dma_priv;
+        struct intel_mid_dma_slave *rxs, *txs;
+        dma_cap_mask_t mask;
+
+        /*
+         * Get pci device for DMA controller, currently it could only
+         * be the DMA controller of either Moorestown or Medfield
+         */
+        dws->dmac = pci_get_device(PCI_VENDOR_ID_INTEL, 0x0813, NULL);
+        if (!dws->dmac)
+                dws->dmac = pci_get_device(PCI_VENDOR_ID_INTEL, 0x0827, NULL);
+
+        dma_cap_zero(mask);
+        dma_cap_set(DMA_SLAVE, mask);
+
+        /* 1. Init rx channel */
+        dws->rxchan = dma_request_channel(mask, mid_spi_dma_chan_filter, dws);
+        if (!dws->rxchan)
+                goto err_exit;
+        rxs = &dw_dma->dmas_rx;
+        rxs->hs_mode = LNW_DMA_HW_HS;
+        rxs->cfg_mode = LNW_DMA_PER_TO_MEM;
+        dws->rxchan->private = rxs;
+
+        /* 2. Init tx channel */
+        dws->txchan = dma_request_channel(mask, mid_spi_dma_chan_filter, dws);
+        if (!dws->txchan)
+                goto free_rxchan;
+        txs = &dw_dma->dmas_tx;
+        txs->hs_mode = LNW_DMA_HW_HS;
+        txs->cfg_mode = LNW_DMA_MEM_TO_PER;
+        dws->txchan->private = txs;
+
+        dws->dma_inited = 1;
+        return 0;
+
+free_rxchan:
+        dma_release_channel(dws->rxchan);
+err_exit:
+        return -1;
+
+}
+
+static void mid_spi_dma_exit(struct dw_spi *dws)
+{
+        dma_release_channel(dws->txchan);
+        dma_release_channel(dws->rxchan);
+}
+
+/*
+ * dws->dma_chan_done is cleared before the dma transfer starts,
+ * callback for rx/tx channel will each increment it by 1.
+ * Reaching 2 means the whole spi transaction is done.
+ */
+static void dw_spi_dma_done(void *arg)
+{
+        struct dw_spi *dws = arg;
+
+        if (++dws->dma_chan_done != 2)
+                return;
+        dw_spi_xfer_done(dws);
+}
+
+static int mid_spi_dma_transfer(struct dw_spi *dws, int cs_change)
+{
+        struct dma_async_tx_descriptor *txdesc = NULL, *rxdesc = NULL;
+        struct dma_chan *txchan, *rxchan;
+        struct dma_slave_config txconf, rxconf;
+        u16 dma_ctrl = 0;
+
+        /* 1. setup DMA related registers */
+        if (cs_change) {
+                spi_enable_chip(dws, 0);
+                dw_writew(dws, dmardlr, 0xf);
+                dw_writew(dws, dmatdlr, 0x10);
+                if (dws->tx_dma)
+                        dma_ctrl |= 0x2;
+                if (dws->rx_dma)
+                        dma_ctrl |= 0x1;
+                dw_writew(dws, dmacr, dma_ctrl);
+                spi_enable_chip(dws, 1);
+        }
+
+        dws->dma_chan_done = 0;
+        txchan = dws->txchan;
+        rxchan = dws->rxchan;
+
+        /* 2. Prepare the TX dma transfer */
+        txconf.direction = DMA_TO_DEVICE;
+        txconf.dst_addr = dws->dma_addr;
+        txconf.dst_maxburst = LNW_DMA_MSIZE_16;
+        txconf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+        txconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+
+        txchan->device->device_control(txchan, DMA_SLAVE_CONFIG,
+                                       (unsigned long) &txconf);
+
+        memset(&dws->tx_sgl, 0, sizeof(dws->tx_sgl));
+        dws->tx_sgl.dma_address = dws->tx_dma;
+        dws->tx_sgl.length = dws->len;
+
+        txdesc = txchan->device->device_prep_slave_sg(txchan,
+                                &dws->tx_sgl,
+                                1,
+                                DMA_TO_DEVICE,
+                                DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_DEST_UNMAP);
+        txdesc->callback = dw_spi_dma_done;
+        txdesc->callback_param = dws;
+
+        /* 3. Prepare the RX dma transfer */
+        rxconf.direction = DMA_FROM_DEVICE;
+        rxconf.src_addr = dws->dma_addr;
+        rxconf.src_maxburst = LNW_DMA_MSIZE_16;
+        rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+        rxconf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+
+        rxchan->device->device_control(rxchan, DMA_SLAVE_CONFIG,
+                                       (unsigned long) &rxconf);
+
+        memset(&dws->rx_sgl, 0, sizeof(dws->rx_sgl));
+        dws->rx_sgl.dma_address = dws->rx_dma;
+        dws->rx_sgl.length = dws->len;
+
+        rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
+                                &dws->rx_sgl,
+                                1,
+                                DMA_FROM_DEVICE,
+                                DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_DEST_UNMAP);
+        rxdesc->callback = dw_spi_dma_done;
+        rxdesc->callback_param = dws;
+
+        /* rx must be started before tx due to spi instinct */
+        rxdesc->tx_submit(rxdesc);
+        txdesc->tx_submit(txdesc);
+        return 0;
+}
+
+static struct dw_spi_dma_ops mid_dma_ops = {
+        .dma_init       = mid_spi_dma_init,
+        .dma_exit       = mid_spi_dma_exit,
+        .dma_transfer   = mid_spi_dma_transfer,
+};
+#endif
+
+/* Some specific info for SPI0 controller on Moorestown */
+
+/* HW info for MRST CLk Control Unit, one 32b reg */
+#define MRST_SPI_CLK_BASE       100000000       /* 100m */
+#define MRST_CLK_SPI0_REG       0xff11d86c
+#define CLK_SPI_BDIV_OFFSET     0
+#define CLK_SPI_BDIV_MASK       0x00000007
+#define CLK_SPI_CDIV_OFFSET     9
+#define CLK_SPI_CDIV_MASK       0x00000e00
+#define CLK_SPI_DISABLE_OFFSET  8
+
+int dw_spi_mid_init(struct dw_spi *dws)
+{
+        u32 *clk_reg, clk_cdiv;
+
+        clk_reg = ioremap_nocache(MRST_CLK_SPI0_REG, 16);
+        if (!clk_reg)
+                return -ENOMEM;
+
+        /* get SPI controller operating freq info */
+        clk_cdiv  = (readl(clk_reg) & CLK_SPI_CDIV_MASK) >> CLK_SPI_CDIV_OFFSET;
+        dws->max_freq = MRST_SPI_CLK_BASE / (clk_cdiv + 1);
+        iounmap(clk_reg);
+
+        dws->num_cs = 16;
+        dws->fifo_len = 40;     /* FIFO has 40 words buffer */
+
+#ifdef CONFIG_SPI_DW_MID_DMA
+        dws->dma_priv = kzalloc(sizeof(struct mid_dma), GFP_KERNEL);
+        if (!dws->dma_priv)
+                return -ENOMEM;
+        dws->dma_ops = &mid_dma_ops;
+#endif
+        return 0;
+}