Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1832 insertions, 0 deletions

diff --git a/drivers/serial/mpsc.c b/drivers/serial/mpsc.c
new file mode 100644
index 000000000000..d0dfc3cf9245
--- /dev/null
+++ b/drivers/serial/mpsc.c
@@ -0,0 +1,1832 @@
+/*
+ * drivers/serial/mpsc.c
+ *
+ * Generic driver for the MPSC (UART mode) on Marvell parts (e.g., GT64240,
+ * GT64260, MV64340, MV64360, GT96100, ... ).
+ *
+ * Author: Mark A. Greer <mgreer@mvista.com>
+ *
+ * Based on an old MPSC driver that was in the linuxppc tree.  It appears to
+ * have been created by Chris Zankel (formerly of MontaVista) but there
+ * is no proper Copyright so I'm not sure.  Apparently, parts were also
+ * taken from PPCBoot (now U-Boot).  Also based on drivers/serial/8250.c
+ * by Russell King.
+ *
+ * 2004 (c) MontaVista, Software, Inc.  This file is licensed under
+ * the terms of the GNU General Public License version 2.  This program
+ * is licensed "as is" without any warranty of any kind, whether express
+ * or implied.
+ */
+/*
+ * The MPSC interface is much like a typical network controller's interface.
+ * That is, you set up separate rings of descriptors for transmitting and
+ * receiving data.  There is also a pool of buffers with (one buffer per
+ * descriptor) that incoming data are dma'd into or outgoing data are dma'd
+ * out of.
+ *
+ * The MPSC requires two other controllers to be able to work.  The Baud Rate
+ * Generator (BRG) provides a clock at programmable frequencies which determines
+ * the baud rate.  The Serial DMA Controller (SDMA) takes incoming data from the
+ * MPSC and DMA's it into memory or DMA's outgoing data and passes it to the
+ * MPSC.  It is actually the SDMA interrupt that the driver uses to keep the
+ * transmit and receive "engines" going (i.e., indicate data has been
+ * transmitted or received).
+ *
+ * NOTES:
+ *
+ * 1) Some chips have an erratum where several regs cannot be
+ * read.  To work around that, we keep a local copy of those regs in
+ * 'mpsc_port_info'.
+ *
+ * 2) Some chips have an erratum where the ctlr will hang when the SDMA ctlr
+ * accesses system mem with coherency enabled.  For that reason, the driver
+ * assumes that coherency for that ctlr has been disabled.  This means
+ * that when in a cache coherent system, the driver has to manually manage
+ * the data cache on the areas that it touches because the dma_* macro are
+ * basically no-ops.
+ *
+ * 3) There is an erratum (on PPC) where you can't use the instruction to do
+ * a DMA_TO_DEVICE/cache clean so DMA_BIDIRECTIONAL/flushes are used in places
+ * where a DMA_TO_DEVICE/clean would have [otherwise] sufficed.
+ *
+ * 4) AFAICT, hardware flow control isn't supported by the controller --MAG.
+ */
+
+#include "mpsc.h"
+
+/*
+ * Define how this driver is known to the outside (we've been assigned a
+ * range on the "Low-density serial ports" major).
+ */
+#define MPSC_MAJOR		204
+#define MPSC_MINOR_START	44
+#define	MPSC_DRIVER_NAME	"MPSC"
+#define	MPSC_DEVFS_NAME		"ttymm/"
+#define	MPSC_DEV_NAME		"ttyMM"
+#define	MPSC_VERSION		"1.00"
+
+static struct mpsc_port_info mpsc_ports[MPSC_NUM_CTLRS];
+static struct mpsc_shared_regs mpsc_shared_regs;
+
+/*
+ ******************************************************************************
+ *
+ * Baud Rate Generator Routines (BRG)
+ *
+ ******************************************************************************
+ */
+static void
+mpsc_brg_init(struct mpsc_port_info *pi, u32 clk_src)
+{
+	u32	v;
+
+	v = (pi->mirror_regs) ? pi->BRG_BCR_m : readl(pi->brg_base + BRG_BCR);
+	v = (v & ~(0xf << 18)) | ((clk_src & 0xf) << 18);
+
+	if (pi->brg_can_tune)
+		v &= ~(1 << 25);
+
+	if (pi->mirror_regs)
+		pi->BRG_BCR_m = v;
+	writel(v, pi->brg_base + BRG_BCR);
+
+	writel(readl(pi->brg_base + BRG_BTR) & 0xffff0000,
+		pi->brg_base + BRG_BTR);
+	return;
+}
+
+static void
+mpsc_brg_enable(struct mpsc_port_info *pi)
+{
+	u32	v;
+
+	v = (pi->mirror_regs) ? pi->BRG_BCR_m : readl(pi->brg_base + BRG_BCR);
+	v |= (1 << 16);
+
+	if (pi->mirror_regs)
+		pi->BRG_BCR_m = v;
+	writel(v, pi->brg_base + BRG_BCR);
+	return;
+}
+
+static void
+mpsc_brg_disable(struct mpsc_port_info *pi)
+{
+	u32	v;
+
+	v = (pi->mirror_regs) ? pi->BRG_BCR_m : readl(pi->brg_base + BRG_BCR);
+	v &= ~(1 << 16);
+
+	if (pi->mirror_regs)
+		pi->BRG_BCR_m = v;
+	writel(v, pi->brg_base + BRG_BCR);
+	return;
+}
+
+static inline void
+mpsc_set_baudrate(struct mpsc_port_info *pi, u32 baud)
+{
+	/*
+	 * To set the baud, we adjust the CDV field in the BRG_BCR reg.
+	 * From manual: Baud = clk / ((CDV+1)*2) ==> CDV = (clk / (baud*2)) - 1.
+	 * However, the input clock is divided by 16 in the MPSC b/c of how
+	 * 'MPSC_MMCRH' was set up so we have to divide the 'clk' used in our
+	 * calculation by 16 to account for that.  So the real calculation
+	 * that accounts for the way the mpsc is set up is:
+	 * CDV = (clk / (baud*2*16)) - 1 ==> CDV = (clk / (baud << 5)) - 1.
+	 */
+	u32	cdv = (pi->port.uartclk / (baud << 5)) - 1;
+	u32	v;
+
+	mpsc_brg_disable(pi);
+	v = (pi->mirror_regs) ? pi->BRG_BCR_m : readl(pi->brg_base + BRG_BCR);
+	v = (v & 0xffff0000) | (cdv & 0xffff);
+
+	if (pi->mirror_regs)
+		pi->BRG_BCR_m = v;
+	writel(v, pi->brg_base + BRG_BCR);
+	mpsc_brg_enable(pi);
+
+	return;
+}
+
+/*
+ ******************************************************************************
+ *
+ * Serial DMA Routines (SDMA)
+ *
+ ******************************************************************************
+ */
+
+static void
+mpsc_sdma_burstsize(struct mpsc_port_info *pi, u32 burst_size)
+{
+	u32	v;
+
+	pr_debug("mpsc_sdma_burstsize[%d]: burst_size: %d\n",
+	    pi->port.line, burst_size);
+
+	burst_size >>= 3; /* Divide by 8 b/c reg values are 8-byte chunks */
+
+	if (burst_size < 2)
+		v = 0x0;	/* 1 64-bit word */
+	else if (burst_size < 4)
+		v = 0x1;	/* 2 64-bit words */
+	else if (burst_size < 8)
+		v = 0x2;	/* 4 64-bit words */
+	else
+		v = 0x3;	/* 8 64-bit words */
+
+	writel((readl(pi->sdma_base + SDMA_SDC) & (0x3 << 12)) | (v << 12),
+		pi->sdma_base + SDMA_SDC);
+	return;
+}
+
+static void
+mpsc_sdma_init(struct mpsc_port_info *pi, u32 burst_size)
+{
+	pr_debug("mpsc_sdma_init[%d]: burst_size: %d\n", pi->port.line,
+		burst_size);
+
+	writel((readl(pi->sdma_base + SDMA_SDC) & 0x3ff) | 0x03f,
+		pi->sdma_base + SDMA_SDC);
+	mpsc_sdma_burstsize(pi, burst_size);
+	return;
+}
+
+static inline u32
+mpsc_sdma_intr_mask(struct mpsc_port_info *pi, u32 mask)
+{
+	u32	old, v;
+
+	pr_debug("mpsc_sdma_intr_mask[%d]: mask: 0x%x\n", pi->port.line, mask);
+
+	old = v = (pi->mirror_regs) ? pi->shared_regs->SDMA_INTR_MASK_m :
+		readl(pi->shared_regs->sdma_intr_base + SDMA_INTR_MASK);
+
+	mask &= 0xf;
+	if (pi->port.line)
+		mask <<= 8;
+	v &= ~mask;
+
+	if (pi->mirror_regs)
+		pi->shared_regs->SDMA_INTR_MASK_m = v;
+	writel(v, pi->shared_regs->sdma_intr_base + SDMA_INTR_MASK);
+
+	if (pi->port.line)
+		old >>= 8;
+	return old & 0xf;
+}
+
+static inline void
+mpsc_sdma_intr_unmask(struct mpsc_port_info *pi, u32 mask)
+{
+	u32	v;
+
+	pr_debug("mpsc_sdma_intr_unmask[%d]: mask: 0x%x\n", pi->port.line,mask);
+
+	v = (pi->mirror_regs) ? pi->shared_regs->SDMA_INTR_MASK_m :
+		readl(pi->shared_regs->sdma_intr_base + SDMA_INTR_MASK);
+
+	mask &= 0xf;
+	if (pi->port.line)
+		mask <<= 8;
+	v |= mask;
+
+	if (pi->mirror_regs)
+		pi->shared_regs->SDMA_INTR_MASK_m = v;
+	writel(v, pi->shared_regs->sdma_intr_base + SDMA_INTR_MASK);
+	return;
+}
+
+static inline void
+mpsc_sdma_intr_ack(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_sdma_intr_ack[%d]: Acknowledging IRQ\n", pi->port.line);
+
+	if (pi->mirror_regs)
+		pi->shared_regs->SDMA_INTR_CAUSE_m = 0;
+	writel(0, pi->shared_regs->sdma_intr_base + SDMA_INTR_CAUSE);
+	return;
+}
+
+static inline void
+mpsc_sdma_set_rx_ring(struct mpsc_port_info *pi, struct mpsc_rx_desc *rxre_p)
+{
+	pr_debug("mpsc_sdma_set_rx_ring[%d]: rxre_p: 0x%x\n",
+		pi->port.line, (u32) rxre_p);
+
+	writel((u32)rxre_p, pi->sdma_base + SDMA_SCRDP);
+	return;
+}
+
+static inline void
+mpsc_sdma_set_tx_ring(struct mpsc_port_info *pi, struct mpsc_tx_desc *txre_p)
+{
+	writel((u32)txre_p, pi->sdma_base + SDMA_SFTDP);
+	writel((u32)txre_p, pi->sdma_base + SDMA_SCTDP);
+	return;
+}
+
+static inline void
+mpsc_sdma_cmd(struct mpsc_port_info *pi, u32 val)
+{
+	u32	v;
+
+	v = readl(pi->sdma_base + SDMA_SDCM);
+	if (val)
+		v |= val;
+	else
+		v = 0;
+	wmb();
+	writel(v, pi->sdma_base + SDMA_SDCM);
+	wmb();
+	return;
+}
+
+static inline uint
+mpsc_sdma_tx_active(struct mpsc_port_info *pi)
+{
+	return readl(pi->sdma_base + SDMA_SDCM) & SDMA_SDCM_TXD;
+}
+
+static inline void
+mpsc_sdma_start_tx(struct mpsc_port_info *pi)
+{
+	struct mpsc_tx_desc *txre, *txre_p;
+
+	/* If tx isn't running & there's a desc ready to go, start it */
+	if (!mpsc_sdma_tx_active(pi)) {
+		txre = (struct mpsc_tx_desc *)(pi->txr +
+			(pi->txr_tail * MPSC_TXRE_SIZE));
+		dma_cache_sync((void *) txre, MPSC_TXRE_SIZE, DMA_FROM_DEVICE);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			invalidate_dcache_range((ulong)txre,
+				(ulong)txre + MPSC_TXRE_SIZE);
+#endif
+
+		if (be32_to_cpu(txre->cmdstat) & SDMA_DESC_CMDSTAT_O) {
+			txre_p = (struct mpsc_tx_desc *)(pi->txr_p +
+							 (pi->txr_tail *
+							  MPSC_TXRE_SIZE));
+
+			mpsc_sdma_set_tx_ring(pi, txre_p);
+			mpsc_sdma_cmd(pi, SDMA_SDCM_STD | SDMA_SDCM_TXD);
+		}
+	}
+
+	return;
+}
+
+static inline void
+mpsc_sdma_stop(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_sdma_stop[%d]: Stopping SDMA\n", pi->port.line);
+
+	/* Abort any SDMA transfers */
+	mpsc_sdma_cmd(pi, 0);
+	mpsc_sdma_cmd(pi, SDMA_SDCM_AR | SDMA_SDCM_AT);
+
+	/* Clear the SDMA current and first TX and RX pointers */
+	mpsc_sdma_set_tx_ring(pi, 0);
+	mpsc_sdma_set_rx_ring(pi, 0);
+
+	/* Disable interrupts */
+	mpsc_sdma_intr_mask(pi, 0xf);
+	mpsc_sdma_intr_ack(pi);
+
+	return;
+}
+
+/*
+ ******************************************************************************
+ *
+ * Multi-Protocol Serial Controller Routines (MPSC)
+ *
+ ******************************************************************************
+ */
+
+static void
+mpsc_hw_init(struct mpsc_port_info *pi)
+{
+	u32	v;
+
+	pr_debug("mpsc_hw_init[%d]: Initializing hardware\n", pi->port.line);
+
+	/* Set up clock routing */
+	if (pi->mirror_regs) {
+		v = pi->shared_regs->MPSC_MRR_m;
+		v &= ~0x1c7;
+		pi->shared_regs->MPSC_MRR_m = v;
+		writel(v, pi->shared_regs->mpsc_routing_base + MPSC_MRR);
+
+		v = pi->shared_regs->MPSC_RCRR_m;
+		v = (v & ~0xf0f) | 0x100;
+		pi->shared_regs->MPSC_RCRR_m = v;
+		writel(v, pi->shared_regs->mpsc_routing_base + MPSC_RCRR);
+
+		v = pi->shared_regs->MPSC_TCRR_m;
+		v = (v & ~0xf0f) | 0x100;
+		pi->shared_regs->MPSC_TCRR_m = v;
+		writel(v, pi->shared_regs->mpsc_routing_base + MPSC_TCRR);
+	}
+	else {
+		v = readl(pi->shared_regs->mpsc_routing_base + MPSC_MRR);
+		v &= ~0x1c7;
+		writel(v, pi->shared_regs->mpsc_routing_base + MPSC_MRR);
+
+		v = readl(pi->shared_regs->mpsc_routing_base + MPSC_RCRR);
+		v = (v & ~0xf0f) | 0x100;
+		writel(v, pi->shared_regs->mpsc_routing_base + MPSC_RCRR);
+
+		v = readl(pi->shared_regs->mpsc_routing_base + MPSC_TCRR);
+		v = (v & ~0xf0f) | 0x100;
+		writel(v, pi->shared_regs->mpsc_routing_base + MPSC_TCRR);
+	}
+
+	/* Put MPSC in UART mode & enabel Tx/Rx egines */
+	writel(0x000004c4, pi->mpsc_base + MPSC_MMCRL);
+
+	/* No preamble, 16x divider, low-latency,  */
+	writel(0x04400400, pi->mpsc_base + MPSC_MMCRH);
+
+	if (pi->mirror_regs) {
+		pi->MPSC_CHR_1_m = 0;
+		pi->MPSC_CHR_2_m = 0;
+	}
+	writel(0, pi->mpsc_base + MPSC_CHR_1);
+	writel(0, pi->mpsc_base + MPSC_CHR_2);
+	writel(pi->mpsc_max_idle, pi->mpsc_base + MPSC_CHR_3);
+	writel(0, pi->mpsc_base + MPSC_CHR_4);
+	writel(0, pi->mpsc_base + MPSC_CHR_5);
+	writel(0, pi->mpsc_base + MPSC_CHR_6);
+	writel(0, pi->mpsc_base + MPSC_CHR_7);
+	writel(0, pi->mpsc_base + MPSC_CHR_8);
+	writel(0, pi->mpsc_base + MPSC_CHR_9);
+	writel(0, pi->mpsc_base + MPSC_CHR_10);
+
+	return;
+}
+
+static inline void
+mpsc_enter_hunt(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_enter_hunt[%d]: Hunting...\n", pi->port.line);
+
+	if (pi->mirror_regs) {
+		writel(pi->MPSC_CHR_2_m | MPSC_CHR_2_EH,
+			pi->mpsc_base + MPSC_CHR_2);
+		/* Erratum prevents reading CHR_2 so just delay for a while */
+		udelay(100);
+	}
+	else {
+		writel(readl(pi->mpsc_base + MPSC_CHR_2) | MPSC_CHR_2_EH,
+			pi->mpsc_base + MPSC_CHR_2);
+
+		while (readl(pi->mpsc_base + MPSC_CHR_2) & MPSC_CHR_2_EH)
+			udelay(10);
+	}
+
+	return;
+}
+
+static inline void
+mpsc_freeze(struct mpsc_port_info *pi)
+{
+	u32	v;
+
+	pr_debug("mpsc_freeze[%d]: Freezing\n", pi->port.line);
+
+	v = (pi->mirror_regs) ? pi->MPSC_MPCR_m :
+		readl(pi->mpsc_base + MPSC_MPCR);
+	v |= MPSC_MPCR_FRZ;
+
+	if (pi->mirror_regs)
+		pi->MPSC_MPCR_m = v;
+	writel(v, pi->mpsc_base + MPSC_MPCR);
+	return;
+}
+
+static inline void
+mpsc_unfreeze(struct mpsc_port_info *pi)
+{
+	u32	v;
+
+	v = (pi->mirror_regs) ? pi->MPSC_MPCR_m :
+		readl(pi->mpsc_base + MPSC_MPCR);
+	v &= ~MPSC_MPCR_FRZ;
+
+	if (pi->mirror_regs)
+		pi->MPSC_MPCR_m = v;
+	writel(v, pi->mpsc_base + MPSC_MPCR);
+
+	pr_debug("mpsc_unfreeze[%d]: Unfrozen\n", pi->port.line);
+	return;
+}
+
+static inline void
+mpsc_set_char_length(struct mpsc_port_info *pi, u32 len)
+{
+	u32	v;
+
+	pr_debug("mpsc_set_char_length[%d]: char len: %d\n", pi->port.line,len);
+
+	v = (pi->mirror_regs) ? pi->MPSC_MPCR_m :
+		readl(pi->mpsc_base + MPSC_MPCR);
+	v = (v & ~(0x3 << 12)) | ((len & 0x3) << 12);
+
+	if (pi->mirror_regs)
+		pi->MPSC_MPCR_m = v;
+	writel(v, pi->mpsc_base + MPSC_MPCR);
+	return;
+}
+
+static inline void
+mpsc_set_stop_bit_length(struct mpsc_port_info *pi, u32 len)
+{
+	u32	v;
+
+	pr_debug("mpsc_set_stop_bit_length[%d]: stop bits: %d\n",
+		pi->port.line, len);
+
+	v = (pi->mirror_regs) ? pi->MPSC_MPCR_m :
+		readl(pi->mpsc_base + MPSC_MPCR);
+
+	v = (v & ~(1 << 14)) | ((len & 0x1) << 14);
+
+	if (pi->mirror_regs)
+		pi->MPSC_MPCR_m = v;
+	writel(v, pi->mpsc_base + MPSC_MPCR);
+	return;
+}
+
+static inline void
+mpsc_set_parity(struct mpsc_port_info *pi, u32 p)
+{
+	u32	v;
+
+	pr_debug("mpsc_set_parity[%d]: parity bits: 0x%x\n", pi->port.line, p);
+
+	v = (pi->mirror_regs) ? pi->MPSC_CHR_2_m :
+		readl(pi->mpsc_base + MPSC_CHR_2);
+
+	p &= 0x3;
+	v = (v & ~0xc000c) | (p << 18) | (p << 2);
+
+	if (pi->mirror_regs)
+		pi->MPSC_CHR_2_m = v;
+	writel(v, pi->mpsc_base + MPSC_CHR_2);
+	return;
+}
+
+/*
+ ******************************************************************************
+ *
+ * Driver Init Routines
+ *
+ ******************************************************************************
+ */
+
+static void
+mpsc_init_hw(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_init_hw[%d]: Initializing\n", pi->port.line);
+
+	mpsc_brg_init(pi, pi->brg_clk_src);
+	mpsc_brg_enable(pi);
+	mpsc_sdma_init(pi, dma_get_cache_alignment());	/* burst a cacheline */
+	mpsc_sdma_stop(pi);
+	mpsc_hw_init(pi);
+
+	return;
+}
+
+static int
+mpsc_alloc_ring_mem(struct mpsc_port_info *pi)
+{
+	int rc = 0;
+	static void mpsc_free_ring_mem(struct mpsc_port_info *pi);
+
+	pr_debug("mpsc_alloc_ring_mem[%d]: Allocating ring mem\n",
+		pi->port.line);
+
+	if (!pi->dma_region) {
+		if (!dma_supported(pi->port.dev, 0xffffffff)) {
+			printk(KERN_ERR "MPSC: Inadequate DMA support\n");
+			rc = -ENXIO;
+		}
+		else if ((pi->dma_region = dma_alloc_noncoherent(pi->port.dev,
+			MPSC_DMA_ALLOC_SIZE, &pi->dma_region_p, GFP_KERNEL))
+			== NULL) {
+
+			printk(KERN_ERR "MPSC: Can't alloc Desc region\n");
+			rc = -ENOMEM;
+		}
+	}
+
+	return rc;
+}
+
+static void
+mpsc_free_ring_mem(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_free_ring_mem[%d]: Freeing ring mem\n", pi->port.line);
+
+	if (pi->dma_region) {
+		dma_free_noncoherent(pi->port.dev, MPSC_DMA_ALLOC_SIZE,
+			  pi->dma_region, pi->dma_region_p);
+		pi->dma_region = NULL;
+		pi->dma_region_p = (dma_addr_t) NULL;
+	}
+
+	return;
+}
+
+static void
+mpsc_init_rings(struct mpsc_port_info *pi)
+{
+	struct mpsc_rx_desc *rxre;
+	struct mpsc_tx_desc *txre;
+	dma_addr_t dp, dp_p;
+	u8 *bp, *bp_p;
+	int i;
+
+	pr_debug("mpsc_init_rings[%d]: Initializing rings\n", pi->port.line);
+
+	BUG_ON(pi->dma_region == NULL);
+
+	memset(pi->dma_region, 0, MPSC_DMA_ALLOC_SIZE);
+
+	/*
+	 * Descriptors & buffers are multiples of cacheline size and must be
+	 * cacheline aligned.
+	 */
+	dp = ALIGN((u32) pi->dma_region, dma_get_cache_alignment());
+	dp_p = ALIGN((u32) pi->dma_region_p, dma_get_cache_alignment());
+
+	/*
+	 * Partition dma region into rx ring descriptor, rx buffers,
+	 * tx ring descriptors, and tx buffers.
+	 */
+	pi->rxr = dp;
+	pi->rxr_p = dp_p;
+	dp += MPSC_RXR_SIZE;
+	dp_p += MPSC_RXR_SIZE;
+
+	pi->rxb = (u8 *) dp;
+	pi->rxb_p = (u8 *) dp_p;
+	dp += MPSC_RXB_SIZE;
+	dp_p += MPSC_RXB_SIZE;
+
+	pi->rxr_posn = 0;
+
+	pi->txr = dp;
+	pi->txr_p = dp_p;
+	dp += MPSC_TXR_SIZE;
+	dp_p += MPSC_TXR_SIZE;
+
+	pi->txb = (u8 *) dp;
+	pi->txb_p = (u8 *) dp_p;
+
+	pi->txr_head = 0;
+	pi->txr_tail = 0;
+
+	/* Init rx ring descriptors */
+	dp = pi->rxr;
+	dp_p = pi->rxr_p;
+	bp = pi->rxb;
+	bp_p = pi->rxb_p;
+
+	for (i = 0; i < MPSC_RXR_ENTRIES; i++) {
+		rxre = (struct mpsc_rx_desc *)dp;
+
+		rxre->bufsize = cpu_to_be16(MPSC_RXBE_SIZE);
+		rxre->bytecnt = cpu_to_be16(0);
+		rxre->cmdstat = cpu_to_be32(SDMA_DESC_CMDSTAT_O |
+					    SDMA_DESC_CMDSTAT_EI |
+					    SDMA_DESC_CMDSTAT_F |
+					    SDMA_DESC_CMDSTAT_L);
+		rxre->link = cpu_to_be32(dp_p + MPSC_RXRE_SIZE);
+		rxre->buf_ptr = cpu_to_be32(bp_p);
+
+		dp += MPSC_RXRE_SIZE;
+		dp_p += MPSC_RXRE_SIZE;
+		bp += MPSC_RXBE_SIZE;
+		bp_p += MPSC_RXBE_SIZE;
+	}
+	rxre->link = cpu_to_be32(pi->rxr_p);	/* Wrap last back to first */
+
+	/* Init tx ring descriptors */
+	dp = pi->txr;
+	dp_p = pi->txr_p;
+	bp = pi->txb;
+	bp_p = pi->txb_p;
+
+	for (i = 0; i < MPSC_TXR_ENTRIES; i++) {
+		txre = (struct mpsc_tx_desc *)dp;
+
+		txre->link = cpu_to_be32(dp_p + MPSC_TXRE_SIZE);
+		txre->buf_ptr = cpu_to_be32(bp_p);
+
+		dp += MPSC_TXRE_SIZE;
+		dp_p += MPSC_TXRE_SIZE;
+		bp += MPSC_TXBE_SIZE;
+		bp_p += MPSC_TXBE_SIZE;
+	}
+	txre->link = cpu_to_be32(pi->txr_p);	/* Wrap last back to first */
+
+	dma_cache_sync((void *) pi->dma_region, MPSC_DMA_ALLOC_SIZE,
+		DMA_BIDIRECTIONAL);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			flush_dcache_range((ulong)pi->dma_region,
+				(ulong)pi->dma_region + MPSC_DMA_ALLOC_SIZE);
+#endif
+
+	return;
+}
+
+static void
+mpsc_uninit_rings(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_uninit_rings[%d]: Uninitializing rings\n",pi->port.line);
+
+	BUG_ON(pi->dma_region == NULL);
+
+	pi->rxr = 0;
+	pi->rxr_p = 0;
+	pi->rxb = NULL;
+	pi->rxb_p = NULL;
+	pi->rxr_posn = 0;
+
+	pi->txr = 0;
+	pi->txr_p = 0;
+	pi->txb = NULL;
+	pi->txb_p = NULL;
+	pi->txr_head = 0;
+	pi->txr_tail = 0;
+
+	return;
+}
+
+static int
+mpsc_make_ready(struct mpsc_port_info *pi)
+{
+	int rc;
+
+	pr_debug("mpsc_make_ready[%d]: Making cltr ready\n", pi->port.line);
+
+	if (!pi->ready) {
+		mpsc_init_hw(pi);
+		if ((rc = mpsc_alloc_ring_mem(pi)))
+			return rc;
+		mpsc_init_rings(pi);
+		pi->ready = 1;
+	}
+
+	return 0;
+}
+
+/*
+ ******************************************************************************
+ *
+ * Interrupt Handling Routines
+ *
+ ******************************************************************************
+ */
+
+static inline int
+mpsc_rx_intr(struct mpsc_port_info *pi, struct pt_regs *regs)
+{
+	struct mpsc_rx_desc *rxre;
+	struct tty_struct *tty = pi->port.info->tty;
+	u32	cmdstat, bytes_in, i;
+	int	rc = 0;
+	u8	*bp;
+	char	flag = TTY_NORMAL;
+	static void mpsc_start_rx(struct mpsc_port_info *pi);
+
+	pr_debug("mpsc_rx_intr[%d]: Handling Rx intr\n", pi->port.line);
+
+	rxre = (struct mpsc_rx_desc *)(pi->rxr + (pi->rxr_posn*MPSC_RXRE_SIZE));
+
+	dma_cache_sync((void *)rxre, MPSC_RXRE_SIZE, DMA_FROM_DEVICE);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+	if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+		invalidate_dcache_range((ulong)rxre,
+			(ulong)rxre + MPSC_RXRE_SIZE);
+#endif
+
+	/*
+	 * Loop through Rx descriptors handling ones that have been completed.
+	 */
+	while (!((cmdstat = be32_to_cpu(rxre->cmdstat)) & SDMA_DESC_CMDSTAT_O)){
+		bytes_in = be16_to_cpu(rxre->bytecnt);
+
+		/* Following use of tty struct directly is deprecated */
+		if (unlikely((tty->flip.count + bytes_in) >= TTY_FLIPBUF_SIZE)){
+			if (tty->low_latency)
+				tty_flip_buffer_push(tty);
+			/*
+			 * If this failed then we will throw awa the bytes
+			 * but mst do so to clear interrupts.
+			 */
+		}
+
+		bp = pi->rxb + (pi->rxr_posn * MPSC_RXBE_SIZE);
+		dma_cache_sync((void *) bp, MPSC_RXBE_SIZE, DMA_FROM_DEVICE);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			invalidate_dcache_range((ulong)bp,
+				(ulong)bp + MPSC_RXBE_SIZE);
+#endif
+
+		/*
+		 * Other than for parity error, the manual provides little
+		 * info on what data will be in a frame flagged by any of
+		 * these errors.  For parity error, it is the last byte in
+		 * the buffer that had the error.  As for the rest, I guess
+		 * we'll assume there is no data in the buffer.
+		 * If there is...it gets lost.
+		 */
+		if (unlikely(cmdstat & (SDMA_DESC_CMDSTAT_BR |
+			SDMA_DESC_CMDSTAT_FR | SDMA_DESC_CMDSTAT_OR))) {
+
+			pi->port.icount.rx++;
+
+			if (cmdstat & SDMA_DESC_CMDSTAT_BR) {	/* Break */
+				pi->port.icount.brk++;
+
+				if (uart_handle_break(&pi->port))
+					goto next_frame;
+			}
+			else if (cmdstat & SDMA_DESC_CMDSTAT_FR)/* Framing */
+				pi->port.icount.frame++;
+			else if (cmdstat & SDMA_DESC_CMDSTAT_OR) /* Overrun */
+				pi->port.icount.overrun++;
+
+			cmdstat &= pi->port.read_status_mask;
+
+			if (cmdstat & SDMA_DESC_CMDSTAT_BR)
+				flag = TTY_BREAK;
+			else if (cmdstat & SDMA_DESC_CMDSTAT_FR)
+				flag = TTY_FRAME;
+			else if (cmdstat & SDMA_DESC_CMDSTAT_OR)
+				flag = TTY_OVERRUN;
+			else if (cmdstat & SDMA_DESC_CMDSTAT_PE)
+				flag = TTY_PARITY;
+		}
+
+		if (uart_handle_sysrq_char(&pi->port, *bp, regs)) {
+			bp++;
+			bytes_in--;
+			goto next_frame;
+		}
+
+		if ((unlikely(cmdstat & (SDMA_DESC_CMDSTAT_BR |
+			SDMA_DESC_CMDSTAT_FR | SDMA_DESC_CMDSTAT_OR))) &&
+			!(cmdstat & pi->port.ignore_status_mask))
+
+			tty_insert_flip_char(tty, *bp, flag);
+		else {
+			for (i=0; i<bytes_in; i++)
+				tty_insert_flip_char(tty, *bp++, TTY_NORMAL);
+
+			pi->port.icount.rx += bytes_in;
+		}
+
+next_frame:
+		rxre->bytecnt = cpu_to_be16(0);
+		wmb();
+		rxre->cmdstat = cpu_to_be32(SDMA_DESC_CMDSTAT_O |
+					    SDMA_DESC_CMDSTAT_EI |
+					    SDMA_DESC_CMDSTAT_F |
+					    SDMA_DESC_CMDSTAT_L);
+		wmb();
+		dma_cache_sync((void *)rxre, MPSC_RXRE_SIZE, DMA_BIDIRECTIONAL);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			flush_dcache_range((ulong)rxre,
+				(ulong)rxre + MPSC_RXRE_SIZE);
+#endif
+
+		/* Advance to next descriptor */
+		pi->rxr_posn = (pi->rxr_posn + 1) & (MPSC_RXR_ENTRIES - 1);
+		rxre = (struct mpsc_rx_desc *)(pi->rxr +
+			(pi->rxr_posn * MPSC_RXRE_SIZE));
+		dma_cache_sync((void *)rxre, MPSC_RXRE_SIZE, DMA_FROM_DEVICE);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			invalidate_dcache_range((ulong)rxre,
+				(ulong)rxre + MPSC_RXRE_SIZE);
+#endif
+
+		rc = 1;
+	}
+
+	/* Restart rx engine, if its stopped */
+	if ((readl(pi->sdma_base + SDMA_SDCM) & SDMA_SDCM_ERD) == 0)
+		mpsc_start_rx(pi);
+
+	tty_flip_buffer_push(tty);
+	return rc;
+}
+
+static inline void
+mpsc_setup_tx_desc(struct mpsc_port_info *pi, u32 count, u32 intr)
+{
+	struct mpsc_tx_desc *txre;
+
+	txre = (struct mpsc_tx_desc *)(pi->txr +
+		(pi->txr_head * MPSC_TXRE_SIZE));
+
+	txre->bytecnt = cpu_to_be16(count);
+	txre->shadow = txre->bytecnt;
+	wmb();			/* ensure cmdstat is last field updated */
+	txre->cmdstat = cpu_to_be32(SDMA_DESC_CMDSTAT_O | SDMA_DESC_CMDSTAT_F |
+				    SDMA_DESC_CMDSTAT_L | ((intr) ?
+							   SDMA_DESC_CMDSTAT_EI
+							   : 0));
+	wmb();
+	dma_cache_sync((void *) txre, MPSC_TXRE_SIZE, DMA_BIDIRECTIONAL);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+	if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+		flush_dcache_range((ulong)txre,
+			(ulong)txre + MPSC_TXRE_SIZE);
+#endif
+
+	return;
+}
+
+static inline void
+mpsc_copy_tx_data(struct mpsc_port_info *pi)
+{
+	struct circ_buf *xmit = &pi->port.info->xmit;
+	u8 *bp;
+	u32 i;
+
+	/* Make sure the desc ring isn't full */
+	while (CIRC_CNT(pi->txr_head, pi->txr_tail, MPSC_TXR_ENTRIES) <
+	       (MPSC_TXR_ENTRIES - 1)) {
+		if (pi->port.x_char) {
+			/*
+			 * Ideally, we should use the TCS field in
+			 * CHR_1 to put the x_char out immediately but
+			 * errata prevents us from being able to read
+			 * CHR_2 to know that its safe to write to
+			 * CHR_1.  Instead, just put it in-band with
+			 * all the other Tx data.
+			 */
+			bp = pi->txb + (pi->txr_head * MPSC_TXBE_SIZE);
+			*bp = pi->port.x_char;
+			pi->port.x_char = 0;
+			i = 1;
+		}
+		else if (!uart_circ_empty(xmit) && !uart_tx_stopped(&pi->port)){
+			i = min((u32) MPSC_TXBE_SIZE,
+				(u32) uart_circ_chars_pending(xmit));
+			i = min(i, (u32) CIRC_CNT_TO_END(xmit->head, xmit->tail,
+				UART_XMIT_SIZE));
+			bp = pi->txb + (pi->txr_head * MPSC_TXBE_SIZE);
+			memcpy(bp, &xmit->buf[xmit->tail], i);
+			xmit->tail = (xmit->tail + i) & (UART_XMIT_SIZE - 1);
+
+			if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+				uart_write_wakeup(&pi->port);
+		}
+		else /* All tx data copied into ring bufs */
+			return;
+
+		dma_cache_sync((void *) bp, MPSC_TXBE_SIZE, DMA_BIDIRECTIONAL);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			flush_dcache_range((ulong)bp,
+				(ulong)bp + MPSC_TXBE_SIZE);
+#endif
+		mpsc_setup_tx_desc(pi, i, 1);
+
+		/* Advance to next descriptor */
+		pi->txr_head = (pi->txr_head + 1) & (MPSC_TXR_ENTRIES - 1);
+	}
+
+	return;
+}
+
+static inline int
+mpsc_tx_intr(struct mpsc_port_info *pi)
+{
+	struct mpsc_tx_desc *txre;
+	int rc = 0;
+
+	if (!mpsc_sdma_tx_active(pi)) {
+		txre = (struct mpsc_tx_desc *)(pi->txr +
+			(pi->txr_tail * MPSC_TXRE_SIZE));
+
+		dma_cache_sync((void *) txre, MPSC_TXRE_SIZE, DMA_FROM_DEVICE);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+		if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+			invalidate_dcache_range((ulong)txre,
+				(ulong)txre + MPSC_TXRE_SIZE);
+#endif
+
+		while (!(be32_to_cpu(txre->cmdstat) & SDMA_DESC_CMDSTAT_O)) {
+			rc = 1;
+			pi->port.icount.tx += be16_to_cpu(txre->bytecnt);
+			pi->txr_tail = (pi->txr_tail+1) & (MPSC_TXR_ENTRIES-1);
+
+			/* If no more data to tx, fall out of loop */
+			if (pi->txr_head == pi->txr_tail)
+				break;
+
+			txre = (struct mpsc_tx_desc *)(pi->txr +
+				(pi->txr_tail * MPSC_TXRE_SIZE));
+			dma_cache_sync((void *) txre, MPSC_TXRE_SIZE,
+				DMA_FROM_DEVICE);
+#if defined(CONFIG_PPC32) && !defined(CONFIG_NOT_COHERENT_CACHE)
+			if (pi->cache_mgmt) /* GT642[46]0 Res #COMM-2 */
+				invalidate_dcache_range((ulong)txre,
+					(ulong)txre + MPSC_TXRE_SIZE);
+#endif
+		}
+
+		mpsc_copy_tx_data(pi);
+		mpsc_sdma_start_tx(pi);	/* start next desc if ready */
+	}
+
+	return rc;
+}
+
+/*
+ * This is the driver's interrupt handler.  To avoid a race, we first clear
+ * the interrupt, then handle any completed Rx/Tx descriptors.  When done
+ * handling those descriptors, we restart the Rx/Tx engines if they're stopped.
+ */
+static irqreturn_t
+mpsc_sdma_intr(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct mpsc_port_info *pi = dev_id;
+	ulong iflags;
+	int rc = IRQ_NONE;
+
+	pr_debug("mpsc_sdma_intr[%d]: SDMA Interrupt Received\n",pi->port.line);
+
+	spin_lock_irqsave(&pi->port.lock, iflags);
+	mpsc_sdma_intr_ack(pi);
+	if (mpsc_rx_intr(pi, regs))
+		rc = IRQ_HANDLED;
+	if (mpsc_tx_intr(pi))
+		rc = IRQ_HANDLED;
+	spin_unlock_irqrestore(&pi->port.lock, iflags);
+
+	pr_debug("mpsc_sdma_intr[%d]: SDMA Interrupt Handled\n", pi->port.line);
+	return rc;
+}
+
+/*
+ ******************************************************************************
+ *
+ * serial_core.c Interface routines
+ *
+ ******************************************************************************
+ */
+static uint
+mpsc_tx_empty(struct uart_port *port)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+	ulong iflags;
+	uint rc;
+
+	spin_lock_irqsave(&pi->port.lock, iflags);
+	rc = mpsc_sdma_tx_active(pi) ? 0 : TIOCSER_TEMT;
+	spin_unlock_irqrestore(&pi->port.lock, iflags);
+
+	return rc;
+}
+
+static void
+mpsc_set_mctrl(struct uart_port *port, uint mctrl)
+{
+	/* Have no way to set modem control lines AFAICT */
+	return;
+}
+
+static uint
+mpsc_get_mctrl(struct uart_port *port)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+	u32 mflags, status;
+	ulong iflags;
+
+	spin_lock_irqsave(&pi->port.lock, iflags);
+	status = (pi->mirror_regs) ? pi->MPSC_CHR_10_m :
+		readl(pi->mpsc_base + MPSC_CHR_10);
+	spin_unlock_irqrestore(&pi->port.lock, iflags);
+
+	mflags = 0;
+	if (status & 0x1)
+		mflags |= TIOCM_CTS;
+	if (status & 0x2)
+		mflags |= TIOCM_CAR;
+
+	return mflags | TIOCM_DSR;	/* No way to tell if DSR asserted */
+}
+
+static void
+mpsc_stop_tx(struct uart_port *port, uint tty_start)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+
+	pr_debug("mpsc_stop_tx[%d]: tty_start: %d\n", port->line, tty_start);
+
+	mpsc_freeze(pi);
+	return;
+}
+
+static void
+mpsc_start_tx(struct uart_port *port, uint tty_start)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+
+	mpsc_unfreeze(pi);
+	mpsc_copy_tx_data(pi);
+	mpsc_sdma_start_tx(pi);
+
+	pr_debug("mpsc_start_tx[%d]: tty_start: %d\n", port->line, tty_start);
+	return;
+}
+
+static void
+mpsc_start_rx(struct mpsc_port_info *pi)
+{
+	pr_debug("mpsc_start_rx[%d]: Starting...\n", pi->port.line);
+
+	if (pi->rcv_data) {
+		mpsc_enter_hunt(pi);
+		mpsc_sdma_cmd(pi, SDMA_SDCM_ERD);
+	}
+	return;
+}
+
+static void
+mpsc_stop_rx(struct uart_port *port)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+
+	pr_debug("mpsc_stop_rx[%d]: Stopping...\n", port->line);
+
+	mpsc_sdma_cmd(pi, SDMA_SDCM_AR);
+	return;
+}
+
+static void
+mpsc_enable_ms(struct uart_port *port)
+{
+	return;			/* Not supported */
+}
+
+static void
+mpsc_break_ctl(struct uart_port *port, int ctl)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+	ulong	flags;
+	u32	v;
+
+	v = ctl ? 0x00ff0000 : 0;
+
+	spin_lock_irqsave(&pi->port.lock, flags);
+	if (pi->mirror_regs)
+		pi->MPSC_CHR_1_m = v;
+	writel(v, pi->mpsc_base + MPSC_CHR_1);
+	spin_unlock_irqrestore(&pi->port.lock, flags);
+
+	return;
+}
+
+static int
+mpsc_startup(struct uart_port *port)
+{
+	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
+	u32 flag = 0;
+	int rc;
+
+	pr_debug("mpsc_startup[%d]: Starting up MPSC, irq: %d\n",
+		port->line, pi->port.irq);
+
+	if ((rc = mpsc_make_ready(pi)) == 0) {
+		/* Setup IRQ handler */
+		mpsc_sdma_intr_ack(pi);
+
+		/* If irq's are shared, need to set flag */
+		if (mpsc_ports[0].port.irq == mpsc_ports[1].port.irq)
+			flag = SA_SHIRQ;
+
+		if (request_irq(pi->port.irq, mpsc_sdma_intr, flag,