[ARM] pata_pxa: DMA-capable PATA driver

This patch adds a driver for a harddrive attached to PXA address and data bus.
Unlike pata_platform, this driver allows usage of PXA DMA controller, making the
transmission speed 3x higher.

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

1 files changed, 411 insertions, 0 deletions

diff --git a/drivers/ata/pata_pxa.c b/drivers/ata/pata_pxa.c
new file mode 100644
index 000000000000..1898c6ed4b4e
--- /dev/null
+++ b/drivers/ata/pata_pxa.c
@@ -0,0 +1,411 @@
+/*
+ * Generic PXA PATA driver
+ *
+ * Copyright (C) 2010 Marek Vasut <marek.vasut@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that 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; see the file COPYING.  If not, write to
+ *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/ata.h>
+#include <linux/libata.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/slab.h>
+#include <linux/completion.h>
+
+#include <scsi/scsi_host.h>
+
+#include <mach/pxa2xx-regs.h>
+#include <mach/pata_pxa.h>
+#include <mach/dma.h>
+
+#define DRV_NAME        "pata_pxa"
+#define DRV_VERSION     "0.1"
+
+struct pata_pxa_data {
+        uint32_t                dma_channel;
+        struct pxa_dma_desc     *dma_desc;
+        dma_addr_t              dma_desc_addr;
+        uint32_t                dma_desc_id;
+
+        /* DMA IO physical address */
+        uint32_t                dma_io_addr;
+        /* PXA DREQ<0:2> pin selector */
+        uint32_t                dma_dreq;
+        /* DMA DCSR register value */
+        uint32_t                dma_dcsr;
+
+        struct completion       dma_done;
+};
+
+/*
+ * Setup the DMA descriptors. The size is transfer capped at 4k per descriptor,
+ * if the transfer is longer, it is split into multiple chained descriptors.
+ */
+static void pxa_load_dmac(struct scatterlist *sg, struct ata_queued_cmd *qc)
+{
+        struct pata_pxa_data *pd = qc->ap->private_data;
+
+        uint32_t cpu_len, seg_len;
+        dma_addr_t cpu_addr;
+
+        cpu_addr = sg_dma_address(sg);
+        cpu_len = sg_dma_len(sg);
+
+        do {
+                seg_len = (cpu_len > 0x1000) ? 0x1000 : cpu_len;
+
+                pd->dma_desc[pd->dma_desc_id].ddadr = pd->dma_desc_addr +
+                        ((pd->dma_desc_id + 1) * sizeof(struct pxa_dma_desc));
+
+                pd->dma_desc[pd->dma_desc_id].dcmd = DCMD_BURST32 |
+                                        DCMD_WIDTH2 | (DCMD_LENGTH & seg_len);
+
+                if (qc->tf.flags & ATA_TFLAG_WRITE) {
+                        pd->dma_desc[pd->dma_desc_id].dsadr = cpu_addr;
+                        pd->dma_desc[pd->dma_desc_id].dtadr = pd->dma_io_addr;
+                        pd->dma_desc[pd->dma_desc_id].dcmd |= DCMD_INCSRCADDR |
+                                                DCMD_FLOWTRG;
+                } else {
+                        pd->dma_desc[pd->dma_desc_id].dsadr = pd->dma_io_addr;
+                        pd->dma_desc[pd->dma_desc_id].dtadr = cpu_addr;
+                        pd->dma_desc[pd->dma_desc_id].dcmd |= DCMD_INCTRGADDR |
+                                                DCMD_FLOWSRC;
+                }
+
+                cpu_len -= seg_len;
+                cpu_addr += seg_len;
+                pd->dma_desc_id++;
+
+        } while (cpu_len);
+
+        /* Should not happen */
+        if (seg_len & 0x1f)
+                DALGN |= (1 << pd->dma_dreq);
+}
+
+/*
+ * Prepare taskfile for submission.
+ */
+static void pxa_qc_prep(struct ata_queued_cmd *qc)
+{
+        struct pata_pxa_data *pd = qc->ap->private_data;
+        int si = 0;
+        struct scatterlist *sg;
+
+        if (!(qc->flags & ATA_QCFLAG_DMAMAP))
+                return;
+
+        pd->dma_desc_id = 0;
+
+        DCSR(pd->dma_channel) = 0;
+        DALGN &= ~(1 << pd->dma_dreq);
+
+        for_each_sg(qc->sg, sg, qc->n_elem, si)
+                pxa_load_dmac(sg, qc);
+
+        pd->dma_desc[pd->dma_desc_id - 1].ddadr = DDADR_STOP;
+
+        /* Fire IRQ only at the end of last block */
+        pd->dma_desc[pd->dma_desc_id - 1].dcmd |= DCMD_ENDIRQEN;
+
+        DDADR(pd->dma_channel) = pd->dma_desc_addr;
+        DRCMR(pd->dma_dreq) = DRCMR_MAPVLD | pd->dma_channel;
+
+}
+
+/*
+ * Configure the DMA controller, load the DMA descriptors, but don't start the
+ * DMA controller yet. Only issue the ATA command.
+ */
+static void pxa_bmdma_setup(struct ata_queued_cmd *qc)
+{
+        qc->ap->ops->sff_exec_command(qc->ap, &qc->tf);
+}
+
+/*
+ * Execute the DMA transfer.
+ */
+static void pxa_bmdma_start(struct ata_queued_cmd *qc)
+{
+        struct pata_pxa_data *pd = qc->ap->private_data;
+        init_completion(&pd->dma_done);
+        DCSR(pd->dma_channel) = DCSR_RUN;
+}
+
+/*
+ * Wait until the DMA transfer completes, then stop the DMA controller.
+ */
+static void pxa_bmdma_stop(struct ata_queued_cmd *qc)
+{
+        struct pata_pxa_data *pd = qc->ap->private_data;
+
+        if ((DCSR(pd->dma_channel) & DCSR_RUN) &&
+                wait_for_completion_timeout(&pd->dma_done, HZ))
+                dev_err(qc->ap->dev, "Timeout waiting for DMA completion!");
+
+        DCSR(pd->dma_channel) = 0;
+}
+
+/*
+ * Read DMA status. The bmdma_stop() will take care of properly finishing the
+ * DMA transfer so we always have DMA-complete interrupt here.
+ */
+static unsigned char pxa_bmdma_status(struct ata_port *ap)
+{
+        struct pata_pxa_data *pd = ap->private_data;
+        unsigned char ret = ATA_DMA_INTR;
+
+        if (pd->dma_dcsr & DCSR_BUSERR)
+                ret |= ATA_DMA_ERR;
+
+        return ret;
+}
+
+/*
+ * No IRQ register present so we do nothing.
+ */
+static void pxa_irq_clear(struct ata_port *ap)
+{
+}
+
+/*
+ * Check for ATAPI DMA. ATAPI DMA is unsupported by this driver. It's still
+ * unclear why ATAPI has DMA issues.
+ */
+static int pxa_check_atapi_dma(struct ata_queued_cmd *qc)
+{
+        return -EOPNOTSUPP;
+}
+
+static struct scsi_host_template pxa_ata_sht = {
+        ATA_BMDMA_SHT(DRV_NAME),
+};
+
+static struct ata_port_operations pxa_ata_port_ops = {
+        .inherits               = &ata_bmdma_port_ops,
+        .cable_detect           = ata_cable_40wire,
+
+        .bmdma_setup            = pxa_bmdma_setup,
+        .bmdma_start            = pxa_bmdma_start,
+        .bmdma_stop             = pxa_bmdma_stop,
+        .bmdma_status           = pxa_bmdma_status,
+
+        .check_atapi_dma        = pxa_check_atapi_dma,
+
+        .sff_irq_clear          = pxa_irq_clear,
+
+        .qc_prep                = pxa_qc_prep,
+};
+
+/*
+ * DMA interrupt handler.
+ */
+static void pxa_ata_dma_irq(int dma, void *port)
+{
+        struct ata_port *ap = port;
+        struct pata_pxa_data *pd = ap->private_data;
+
+        pd->dma_dcsr = DCSR(dma);
+        DCSR(dma) = pd->dma_dcsr;
+
+        if (pd->dma_dcsr & DCSR_STOPSTATE)
+                complete(&pd->dma_done);
+}
+
+static int __devinit pxa_ata_probe(struct platform_device *pdev)
+{
+        struct ata_host *host;
+        struct ata_port *ap;
+        struct pata_pxa_data *data;
+        struct resource *cmd_res;
+        struct resource *ctl_res;
+        struct resource *dma_res;
+        struct resource *irq_res;
+        struct pata_pxa_pdata *pdata = pdev->dev.platform_data;
+        int ret = 0;
+
+        /*
+         * Resource validation, three resources are needed:
+         *  - CMD port base address
+         *  - CTL port base address
+         *  - DMA port base address
+         *  - IRQ pin
+         */
+        if (pdev->num_resources != 4) {
+                dev_err(&pdev->dev, "invalid number of resources\n");
+                return -EINVAL;
+        }
+
+        /*
+         * CMD port base address
+         */
+        cmd_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (unlikely(cmd_res == NULL))
+                return -EINVAL;
+
+        /*
+         * CTL port base address
+         */
+        ctl_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+        if (unlikely(ctl_res == NULL))
+                return -EINVAL;
+
+        /*
+         * DMA port base address
+         */
+        dma_res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
+        if (unlikely(dma_res == NULL))
+                return -EINVAL;
+
+        /*
+         * IRQ pin
+         */
+        irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+        if (unlikely(irq_res == NULL))
+                return -EINVAL;
+
+        /*
+         * Allocate the host
+         */
+        host = ata_host_alloc(&pdev->dev, 1);
+        if (!host)
+                return -ENOMEM;
+
+        ap              = host->ports[0];
+        ap->ops         = &pxa_ata_port_ops;
+        ap->pio_mask    = ATA_PIO4;
+        ap->mwdma_mask  = ATA_MWDMA2;
+        ap->flags       = ATA_FLAG_MMIO;
+
+        ap->ioaddr.cmd_addr     = devm_ioremap(&pdev->dev, cmd_res->start,
+                                                resource_size(cmd_res));
+        ap->ioaddr.ctl_addr     = devm_ioremap(&pdev->dev, ctl_res->start,
+                                                resource_size(ctl_res));
+        ap->ioaddr.bmdma_addr   = devm_ioremap(&pdev->dev, dma_res->start,
+                                                resource_size(dma_res));
+
+        /*
+         * Adjust register offsets
+         */
+        ap->ioaddr.altstatus_addr = ap->ioaddr.ctl_addr;
+        ap->ioaddr.data_addr    = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_DATA << pdata->reg_shift);
+        ap->ioaddr.error_addr   = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_ERR << pdata->reg_shift);
+        ap->ioaddr.feature_addr = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_FEATURE << pdata->reg_shift);
+        ap->ioaddr.nsect_addr   = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_NSECT << pdata->reg_shift);
+        ap->ioaddr.lbal_addr    = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_LBAL << pdata->reg_shift);
+        ap->ioaddr.lbam_addr    = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_LBAM << pdata->reg_shift);
+        ap->ioaddr.lbah_addr    = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_LBAH << pdata->reg_shift);
+        ap->ioaddr.device_addr  = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_DEVICE << pdata->reg_shift);
+        ap->ioaddr.status_addr  = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_STATUS << pdata->reg_shift);
+        ap->ioaddr.command_addr = ap->ioaddr.cmd_addr +
+                                        (ATA_REG_CMD << pdata->reg_shift);
+
+        /*
+         * Allocate and load driver's internal data structure
+         */
+        data = devm_kzalloc(&pdev->dev, sizeof(struct pata_pxa_data),
+                                                                GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+
+        ap->private_data = data;
+        data->dma_dreq = pdata->dma_dreq;
+        data->dma_io_addr = dma_res->start;
+
+        /*
+         * Allocate space for the DMA descriptors
+         */
+        data->dma_desc = dmam_alloc_coherent(&pdev->dev, PAGE_SIZE,
+                                        &data->dma_desc_addr, GFP_KERNEL);
+        if (!data->dma_desc)
+                return -EINVAL;
+
+        /*
+         * Request the DMA channel
+         */
+        data->dma_channel = pxa_request_dma(DRV_NAME, DMA_PRIO_LOW,
+                                                pxa_ata_dma_irq, ap);
+        if (data->dma_channel < 0)
+                return -EBUSY;
+
+        /*
+         * Stop and clear the DMA channel
+         */
+        DCSR(data->dma_channel) = 0;
+
+        /*
+         * Activate the ATA host
+         */
+        ret = ata_host_activate(host, irq_res->start, ata_sff_interrupt,
+                                pdata->irq_flags, &pxa_ata_sht);
+        if (ret)
+                pxa_free_dma(data->dma_channel);
+
+        return ret;
+}
+
+static int __devexit pxa_ata_remove(struct platform_device *pdev)
+{
+        struct ata_host *host = dev_get_drvdata(&pdev->dev);
+        struct pata_pxa_data *data = host->ports[0]->private_data;
+
+        pxa_free_dma(data->dma_channel);
+
+        ata_host_detach(host);
+
+        return 0;
+}
+
+static struct platform_driver pxa_ata_driver = {
+        .probe          = pxa_ata_probe,
+        .remove         = __devexit_p(pxa_ata_remove),
+        .driver         = {
+                .name           = DRV_NAME,
+                .owner          = THIS_MODULE,
+        },
+};
+
+static int __init pxa_ata_init(void)
+{
+        return platform_driver_register(&pxa_ata_driver);
+}
+
+static void __exit pxa_ata_exit(void)
+{
+        platform_driver_unregister(&pxa_ata_driver);
+}
+
+module_init(pxa_ata_init);
+module_exit(pxa_ata_exit);
+
+MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
+MODULE_DESCRIPTION("DMA-capable driver for PATA on PXA CPU");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+MODULE_ALIAS("platform:" DRV_NAME);