pasemi: DMA engine management library

pasemi: DMA engine management library

Introduce a DMA management library to manage the various DMA resources
on the PA Semi SoCs. Since several drivers need to allocate these shared
resources, provide some abstractions as well as allocation/free functions
for channels, etc.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 487 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pasemi/dma_lib.c b/arch/powerpc/platforms/pasemi/dma_lib.c
new file mode 100644
index 000000000000..e6e474247dc9
--- /dev/null
+++ b/arch/powerpc/platforms/pasemi/dma_lib.c
@@ -0,0 +1,487 @@
+/*
+ * Copyright (C) 2006-2007 PA Semi, Inc
+ *
+ * Common functions for DMA access on PA Semi PWRficient
+ *
+ * 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.
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/of.h>
+
+#include <asm/pasemi_dma.h>
+
+#define MAX_TXCH 64
+#define MAX_RXCH 64
+
+static struct pasdma_status *dma_status;
+
+static void __iomem *iob_regs;
+static void __iomem *mac_regs[6];
+static void __iomem *dma_regs;
+
+static int base_hw_irq;
+
+static int num_txch, num_rxch;
+
+static struct pci_dev *dma_pdev;
+
+/* Bitmaps to handle allocation of channels */
+
+static DECLARE_BITMAP(txch_free, MAX_TXCH);
+static DECLARE_BITMAP(rxch_free, MAX_RXCH);
+
+/* pasemi_read_iob_reg - read IOB register
+ * @reg: Register to read (offset into PCI CFG space)
+ */
+unsigned int pasemi_read_iob_reg(unsigned int reg)
+{
+	return in_le32(iob_regs+reg);
+}
+EXPORT_SYMBOL(pasemi_read_iob_reg);
+
+/* pasemi_write_iob_reg - write IOB register
+ * @reg: Register to write to (offset into PCI CFG space)
+ * @val: Value to write
+ */
+void pasemi_write_iob_reg(unsigned int reg, unsigned int val)
+{
+	out_le32(iob_regs+reg, val);
+}
+EXPORT_SYMBOL(pasemi_write_iob_reg);
+
+/* pasemi_read_mac_reg - read MAC register
+ * @intf: MAC interface
+ * @reg: Register to read (offset into PCI CFG space)
+ */
+unsigned int pasemi_read_mac_reg(int intf, unsigned int reg)
+{
+	return in_le32(mac_regs[intf]+reg);
+}
+EXPORT_SYMBOL(pasemi_read_mac_reg);
+
+/* pasemi_write_mac_reg - write MAC register
+ * @intf: MAC interface
+ * @reg: Register to write to (offset into PCI CFG space)
+ * @val: Value to write
+ */
+void pasemi_write_mac_reg(int intf, unsigned int reg, unsigned int val)
+{
+	out_le32(mac_regs[intf]+reg, val);
+}
+EXPORT_SYMBOL(pasemi_write_mac_reg);
+
+/* pasemi_read_dma_reg - read DMA register
+ * @reg: Register to read (offset into PCI CFG space)
+ */
+unsigned int pasemi_read_dma_reg(unsigned int reg)
+{
+	return in_le32(dma_regs+reg);
+}
+EXPORT_SYMBOL(pasemi_read_dma_reg);
+
+/* pasemi_write_dma_reg - write DMA register
+ * @reg: Register to write to (offset into PCI CFG space)
+ * @val: Value to write
+ */
+void pasemi_write_dma_reg(unsigned int reg, unsigned int val)
+{
+	out_le32(dma_regs+reg, val);
+}
+EXPORT_SYMBOL(pasemi_write_dma_reg);
+
+static int pasemi_alloc_tx_chan(enum pasemi_dmachan_type type)
+{
+	int bit;
+	int start, limit;
+
+	switch (type & (TXCHAN_EVT0|TXCHAN_EVT1)) {
+	case TXCHAN_EVT0:
+		start = 0;
+		limit = 10;
+		break;
+	case TXCHAN_EVT1:
+		start = 10;
+		limit = MAX_TXCH;
+		break;
+	default:
+		start = 0;
+		limit = MAX_TXCH;
+		break;
+	}
+retry:
+	bit = find_next_bit(txch_free, MAX_TXCH, start);
+	if (bit >= limit)
+		return -ENOSPC;
+	if (!test_and_clear_bit(bit, txch_free))
+		goto retry;
+
+	return bit;
+}
+
+static void pasemi_free_tx_chan(int chan)
+{
+	BUG_ON(test_bit(chan, txch_free));
+	set_bit(chan, txch_free);
+}
+
+static int pasemi_alloc_rx_chan(void)
+{
+	int bit;
+retry:
+	bit = find_first_bit(rxch_free, MAX_RXCH);
+	if (bit >= MAX_TXCH)
+		return -ENOSPC;
+	if (!test_and_clear_bit(bit, rxch_free))
+		goto retry;
+
+	return bit;
+}
+
+static void pasemi_free_rx_chan(int chan)
+{
+	BUG_ON(test_bit(chan, rxch_free));
+	set_bit(chan, rxch_free);
+}
+
+/* pasemi_dma_alloc_chan - Allocate a DMA channel
+ * @type: Type of channel to allocate
+ * @total_size: Total size of structure to allocate (to allow for more
+ *		room behind the structure to be used by the client)
+ * @offset: Offset in bytes from start of the total structure to the beginning
+ *	    of struct pasemi_dmachan. Needed when struct pasemi_dmachan is
+ *	    not the first member of the client structure.
+ *
+ * pasemi_dma_alloc_chan allocates a DMA channel for use by a client. The
+ * type argument specifies whether it's a RX or TX channel, and in the case
+ * of TX channels which group it needs to belong to (if any).
+ *
+ * Returns a pointer to the total structure allocated on success, NULL
+ * on failure.
+ */
+void *pasemi_dma_alloc_chan(enum pasemi_dmachan_type type,
+			    int total_size, int offset)
+{
+	void *buf;
+	struct pasemi_dmachan *chan;
+	int chno;
+
+	BUG_ON(total_size < sizeof(struct pasemi_dmachan));
+
+	buf = kzalloc(total_size, GFP_KERNEL);
+
+	if (!buf)
+		return NULL;
+	chan = buf + offset;
+
+	chan->priv = buf;
+
+	switch (type & (TXCHAN|RXCHAN)) {
+	case RXCHAN:
+		chno = pasemi_alloc_rx_chan();
+		chan->chno = chno;
+		chan->irq = irq_create_mapping(NULL,
+					       base_hw_irq + num_txch + chno);
+		chan->status = &dma_status->rx_sta[chno];
+		break;
+	case TXCHAN:
+		chno = pasemi_alloc_tx_chan(type);
+		chan->chno = chno;
+		chan->irq = irq_create_mapping(NULL, base_hw_irq + chno);
+		chan->status = &dma_status->tx_sta[chno];
+		break;
+	}
+
+	chan->chan_type = type;
+
+	return chan;
+}
+EXPORT_SYMBOL(pasemi_dma_alloc_chan);
+
+/* pasemi_dma_free_chan - Free a previously allocated channel
+ * @chan: Channel to free
+ *
+ * Frees a previously allocated channel. It will also deallocate any
+ * descriptor ring associated with the channel, if allocated.
+ */
+void pasemi_dma_free_chan(struct pasemi_dmachan *chan)
+{
+	if (chan->ring_virt)
+		pasemi_dma_free_ring(chan);
+
+	switch (chan->chan_type & (RXCHAN|TXCHAN)) {
+	case RXCHAN:
+		pasemi_free_rx_chan(chan->chno);
+		break;
+	case TXCHAN:
+		pasemi_free_tx_chan(chan->chno);
+		break;
+	}
+
+	kfree(chan->priv);
+}
+EXPORT_SYMBOL(pasemi_dma_free_chan);
+
+/* pasemi_dma_alloc_ring - Allocate descriptor ring for a channel
+ * @chan: Channel for which to allocate
+ * @ring_size: Ring size in 64-bit (8-byte) words
+ *
+ * Allocate a descriptor ring for a channel. Returns 0 on success, errno
+ * on failure. The passed in struct pasemi_dmachan is updated with the
+ * virtual and DMA addresses of the ring.
+ */
+int pasemi_dma_alloc_ring(struct pasemi_dmachan *chan, int ring_size)
+{
+	BUG_ON(chan->ring_virt);
+
+	chan->ring_size = ring_size;
+
+	chan->ring_virt = dma_alloc_coherent(&dma_pdev->dev,
+					     ring_size * sizeof(u64),
+					     &chan->ring_dma, GFP_KERNEL);
+
+	if (!chan->ring_virt)
+		return -ENOMEM;
+
+	memset(chan->ring_virt, 0, ring_size * sizeof(u64));
+
+	return 0;
+}
+EXPORT_SYMBOL(pasemi_dma_alloc_ring);
+
+/* pasemi_dma_free_ring - Free an allocated descriptor ring for a channel
+ * @chan: Channel for which to free the descriptor ring
+ *
+ * Frees a previously allocated descriptor ring for a channel.
+ */
+void pasemi_dma_free_ring(struct pasemi_dmachan *chan)
+{
+	BUG_ON(!chan->ring_virt);
+
+	dma_free_coherent(&dma_pdev->dev, chan->ring_size * sizeof(u64),
+			  chan->ring_virt, chan->ring_dma);
+	chan->ring_virt = NULL;
+	chan->ring_size = 0;
+	chan->ring_dma = 0;
+}
+EXPORT_SYMBOL(pasemi_dma_free_ring);
+
+/* pasemi_dma_start_chan - Start a DMA channel
+ * @chan: Channel to start
+ * @cmdsta: Additional CCMDSTA/TCMDSTA bits to write
+ *
+ * Enables (starts) a DMA channel with optional additional arguments.
+ */
+void pasemi_dma_start_chan(const struct pasemi_dmachan *chan, const u32 cmdsta)
+{
+	if (chan->chan_type == RXCHAN)
+		pasemi_write_dma_reg(PAS_DMA_RXCHAN_CCMDSTA(chan->chno),
+				     cmdsta | PAS_DMA_RXCHAN_CCMDSTA_EN);
+	else
+		pasemi_write_dma_reg(PAS_DMA_TXCHAN_TCMDSTA(chan->chno),
+				     cmdsta | PAS_DMA_TXCHAN_TCMDSTA_EN);
+}
+EXPORT_SYMBOL(pasemi_dma_start_chan);
+
+/* pasemi_dma_stop_chan - Stop a DMA channel
+ * @chan: Channel to stop
+ *
+ * Stops (disables) a DMA channel. This is done by setting the ST bit in the
+ * CMDSTA register and waiting on the ACT (active) bit to clear, then
+ * finally disabling the whole channel.
+ *
+ * This function will only try for a short while for the channel to stop, if
+ * it doesn't it will return failure.
+ *
+ * Returns 1 on success, 0 on failure.
+ */
+#define MAX_RETRIES 5000
+int pasemi_dma_stop_chan(const struct pasemi_dmachan *chan)
+{
+	int reg, retries;
+	u32 sta;
+
+	if (chan->chan_type == RXCHAN) {
+		reg = PAS_DMA_RXCHAN_CCMDSTA(chan->chno);
+		pasemi_write_dma_reg(reg, PAS_DMA_RXCHAN_CCMDSTA_ST);
+		for (retries = 0; retries < MAX_RETRIES; retries++) {
+			sta = pasemi_read_dma_reg(reg);
+			if (!(sta & PAS_DMA_RXCHAN_CCMDSTA_ACT)) {
+				pasemi_write_dma_reg(reg, 0);
+				return 1;
+			}
+			cond_resched();
+		}
+	} else {
+		reg = PAS_DMA_TXCHAN_TCMDSTA(chan->chno);
+		pasemi_write_dma_reg(reg, PAS_DMA_TXCHAN_TCMDSTA_ST);
+		for (retries = 0; retries < MAX_RETRIES; retries++) {
+			sta = pasemi_read_dma_reg(reg);
+			if (!(sta & PAS_DMA_TXCHAN_TCMDSTA_ACT)) {
+				pasemi_write_dma_reg(reg, 0);
+				return 1;
+			}
+			cond_resched();
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(pasemi_dma_stop_chan);
+
+/* pasemi_dma_alloc_buf - Allocate a buffer to use for DMA
+ * @chan: Channel to allocate for
+ * @size: Size of buffer in bytes
+ * @handle: DMA handle
+ *
+ * Allocate a buffer to be used by the DMA engine for read/write,
+ * similar to dma_alloc_coherent().
+ *
+ * Returns the virtual address of the buffer, or NULL in case of failure.
+ */
+void *pasemi_dma_alloc_buf(struct pasemi_dmachan *chan, int size,
+			   dma_addr_t *handle)
+{
+	return dma_alloc_coherent(&dma_pdev->dev, size, handle, GFP_KERNEL);
+}
+EXPORT_SYMBOL(pasemi_dma_alloc_buf);
+
+/* pasemi_dma_free_buf - Free a buffer used for DMA
+ * @chan: Channel the buffer was allocated for
+ * @size: Size of buffer in bytes
+ * @handle: DMA handle
+ *
+ * Frees a previously allocated buffer.
+ */
+void pasemi_dma_free_buf(struct pasemi_dmachan *chan, int size,
+			 dma_addr_t *handle)
+{
+	dma_free_coherent(&dma_pdev->dev, size, handle, GFP_KERNEL);
+}
+EXPORT_SYMBOL(pasemi_dma_free_buf);
+
+static void *map_onedev(struct pci_dev *p, int index)
+{
+	struct device_node *dn;
+	void __iomem *ret;
+
+	dn = pci_device_to_OF_node(p);
+	if (!dn)
+		goto fallback;
+
+	ret = of_iomap(dn, index);
+	if (!ret)
+		goto fallback;
+
+	return ret;
+fallback:
+	/* This is hardcoded and ugly, but we have some firmware versions
+	 * that don't provide the register space in the device tree. Luckily
+	 * they are at well-known locations so we can just do the math here.
+	 */
+	return ioremap(0xe0000000 + (p->devfn << 12), 0x2000);
+}
+
+/* pasemi_dma_init - Initialize the PA Semi DMA library
+ *
+ * This function initializes the DMA library. It must be called before
+ * any other function in the library.
+ *
+ * Returns 0 on success, errno on failure.
+ */
+int pasemi_dma_init(void)
+{
+	static spinlock_t init_lock = SPIN_LOCK_UNLOCKED;
+	struct pci_dev *iob_pdev;
+	struct pci_dev *pdev;
+	struct resource res;
+	struct device_node *dn;
+	int i, intf, err = 0;
+	u32 tmp;
+
+	if (!machine_is(pasemi))
+		return -ENODEV;
+
+	spin_lock(&init_lock);
+
+	/* Make sure we haven't already initialized */
+	if (dma_pdev)
+		goto out;
+
+	iob_pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa001, NULL);
+	if (!iob_pdev) {
+		BUG();
+		printk(KERN_WARNING "Can't find I/O Bridge\n");
+		err = -ENODEV;
+		goto out;
+	}
+	iob_regs = map_onedev(iob_pdev, 0);
+
+	dma_pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa007, NULL);
+	if (!dma_pdev) {
+		BUG();
+		printk(KERN_WARNING "Can't find DMA controller\n");
+		err = -ENODEV;
+		goto out;
+	}
+	dma_regs = map_onedev(dma_pdev, 0);
+	base_hw_irq = virq_to_hw(dma_pdev->irq);
+
+	pci_read_config_dword(dma_pdev, PAS_DMA_CAP_TXCH, &tmp);
+	num_txch = (tmp & PAS_DMA_CAP_TXCH_TCHN_M) >> PAS_DMA_CAP_TXCH_TCHN_S;
+
+	pci_read_config_dword(dma_pdev, PAS_DMA_CAP_RXCH, &tmp);
+	num_rxch = (tmp & PAS_DMA_CAP_RXCH_RCHN_M) >> PAS_DMA_CAP_RXCH_RCHN_S;
+
+	intf = 0;
+	for (pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa006, NULL);
+	     pdev;
+	     pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa006, pdev))
+		mac_regs[intf++] = map_onedev(pdev, 0);
+
+	pci_dev_put(pdev);
+
+	for (pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa005, NULL);
+	     pdev;
+	     pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa005, pdev))
+		mac_regs[intf++] = map_onedev(pdev, 0);
+
+	pci_dev_put(pdev);
+
+	dn = pci_device_to_OF_node(iob_pdev);
+	if (dn)
+		err = of_address_to_resource(dn, 1, &res);
+	if (!dn || err) {
+		/* Fallback for old firmware */
+		res.start = 0xfd800000;
+		res.end = res.start + 0x1000;
+	}
+	dma_status = __ioremap(res.start, res.end-res.start, 0);
+	pci_dev_put(iob_pdev);
+
+	for (i = 0; i < MAX_TXCH; i++)
+		__set_bit(i, txch_free);
+
+	for (i = 0; i < MAX_RXCH; i++)
+		__set_bit(i, rxch_free);
+
+	printk(KERN_INFO "PA Semi PWRficient DMA library initialized "
+		"(%d tx, %d rx channels)\n", num_txch, num_rxch);
+
+out:
+	spin_unlock(&init_lock);
+	return err;
+}