dma: MIC X100 DMA Driver

This patch implements DMA Engine API for DMA controller on MIC X100
Coprocessors. DMA h/w is shared between host and card s/w.
Channels 0 to 3 are used by host and 4 to 7 are used by card.
Since the DMA device doesn't show up as PCIe device, a virtual bus called mic
bus is created and virtual devices are added on that bus to follow device model.
Allowed dma transfer directions are host to card, card to host and card to card.
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Nikhil Rao <nikhil.rao@intel.com>
Reviewed-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Siva Yerramreddy <yshivakrishna@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/dma/Kconfig

@@ -33,6 +33,25 @@ if DMADEVICES
 
 comment "DMA Devices"
 
+config INTEL_MIC_X100_DMA
+	tristate "Intel MIC X100 DMA Driver"
+	depends on 64BIT && X86 && INTEL_MIC_BUS
+	select DMAENGINE
+	default N
+	help
+	  This enables DMA support for the Intel Many Integrated Core
+	  (MIC) family of PCIe form factor coprocessor X100 devices that
+	  run a 64 bit Linux OS. This driver will be used by both MIC
+	  host and card drivers.
+
+	  If you are building host kernel with a MIC device or a card
+	  kernel for a MIC device, then say M (recommended) or Y, else
+	  say N. If unsure say N.
+
+	  More information about the Intel MIC family as well as the Linux
+	  OS and tools for MIC to use with this driver are available from
+	  <http://software.intel.com/en-us/mic-developer>.
+
 config INTEL_MID_DMAC
 	tristate "Intel MID DMA support for Peripheral DMA controllers"
 	depends on PCI && X86

drivers/dma/Makefile

@@ -47,3 +47,4 @@ obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
 obj-$(CONFIG_FSL_EDMA) += fsl-edma.o
 obj-$(CONFIG_QCOM_BAM_DMA) += qcom_bam_dma.o
 obj-y += xilinx/
+obj-$(CONFIG_INTEL_MIC_X100_DMA) += mic_x100_dma.o

drivers/dma/mic_x100_dma.h

+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * Copyright(c) 2014 Intel Corporation.
+ *
+ * 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.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ * Intel MIC X100 DMA Driver.
+ *
+ * Adapted from IOAT dma driver.
+ */
+#ifndef _MIC_X100_DMA_H_
+#define _MIC_X100_DMA_H_
+
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/debugfs.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/mic_bus.h>
+
+#include "dmaengine.h"
+
+/*
+ * MIC has a total of 8 dma channels.
+ * Four channels are assigned for host SW use & the remaining for MIC SW.
+ * MIC DMA transfer size & addresses need to be 64 byte aligned.
+ */
+#define MIC_DMA_MAX_NUM_CHAN	8
+#define MIC_DMA_NUM_CHAN	4
+#define MIC_DMA_ALIGN_SHIFT	6
+#define MIC_DMA_ALIGN_BYTES	(1 << MIC_DMA_ALIGN_SHIFT)
+#define MIC_DMA_DESC_RX_SIZE	(128 * 1024 - 4)
+
+/*
+ * Register descriptions
+ * All the registers are 32 bit registers.
+ * DCR is a global register and all others are per-channel.
+ * DCR - bits 0, 2, 4, 6, 8, 10, 12, 14 - enable bits for channels 0 to 7
+ *	 bits 1, 3, 5, 7, 9, 11, 13, 15 - owner bits for channels 0 to 7
+ * DCAR - bit 24 & 25 interrupt masks for mic owned & host owned channels
+ * DHPR - head of the descriptor ring updated by s/w
+ * DTPR - tail of the descriptor ring updated by h/w
+ * DRAR_LO - lower 32 bits of descriptor ring's mic address
+ * DRAR_HI - 3:0 - remaining 4 bits of descriptor ring's mic address
+ *	     20:4 descriptor ring size
+ *	     25:21 mic smpt entry number
+ * DSTAT - 16:0 h/w completion count; 31:28 dma engine status
+ * DCHERR - this register is non-zero on error
+ * DCHERRMSK - interrupt mask register
+ */
+#define MIC_DMA_HW_CMP_CNT_MASK		0x1ffff
+#define MIC_DMA_CHAN_QUIESCE		0x20000000
+#define MIC_DMA_SBOX_BASE		0x00010000
+#define MIC_DMA_SBOX_DCR		0x0000A280
+#define MIC_DMA_SBOX_CH_BASE		0x0001A000
+#define MIC_DMA_SBOX_CHAN_OFF		0x40
+#define MIC_DMA_SBOX_DCAR_IM0		(0x1 << 24)
+#define MIC_DMA_SBOX_DCAR_IM1		(0x1 << 25)
+#define MIC_DMA_SBOX_DRARHI_SYS_MASK	(0x1 << 26)
+#define MIC_DMA_REG_DCAR		0
+#define MIC_DMA_REG_DHPR		4
+#define MIC_DMA_REG_DTPR		8
+#define MIC_DMA_REG_DRAR_LO		20
+#define MIC_DMA_REG_DRAR_HI		24
+#define MIC_DMA_REG_DSTAT		32
+#define MIC_DMA_REG_DCHERR		44
+#define MIC_DMA_REG_DCHERRMSK		48
+
+/* HW dma desc */
+struct mic_dma_desc {
+	u64 qw0;
+	u64 qw1;
+};
+
+enum mic_dma_chan_owner {
+	MIC_DMA_CHAN_MIC = 0,
+	MIC_DMA_CHAN_HOST
+};
+
+/*
+ * mic_dma_chan - channel specific information
+ * @ch_num: channel number
+ * @owner: owner of this channel
+ * @last_tail: cached value of descriptor ring tail
+ * @head: index of next descriptor in desc_ring
+ * @issued: hardware notification point
+ * @submitted: index that will be used to submit descriptors to h/w
+ * @api_ch: dma engine api channel
+ * @desc_ring: dma descriptor ring
+ * @desc_ring_micpa: mic physical address of desc_ring
+ * @status_dest: destination for status (fence) descriptor
+ * @status_dest_micpa: mic address for status_dest,
+ *		       DMA controller uses this address
+ * @tx_array: array of async_tx
+ * @cleanup_lock: lock held when processing completed tx
+ * @prep_lock: lock held in prep_memcpy & released in tx_submit
+ * @issue_lock: lock used to synchronize writes to head
+ * @cookie: mic_irq cookie used with mic irq request
+ */
+struct mic_dma_chan {
+	int ch_num;
+	enum mic_dma_chan_owner owner;
+	u32 last_tail;
+	u32 head;
+	u32 issued;
+	u32 submitted;
+	struct dma_chan api_ch;
+	struct mic_dma_desc *desc_ring;
+	dma_addr_t desc_ring_micpa;
+	u64 *status_dest;
+	dma_addr_t status_dest_micpa;
+	struct dma_async_tx_descriptor *tx_array;
+	spinlock_t cleanup_lock;
+	spinlock_t prep_lock;
+	spinlock_t issue_lock;
+	struct mic_irq *cookie;
+};
+
+/*
+ * struct mic_dma_device - per mic device
+ * @mic_ch: dma channels
+ * @dma_dev: underlying dma device
+ * @mbdev: mic bus dma device
+ * @mmio: virtual address of the mmio space
+ * @dbg_dir: debugfs directory
+ * @start_ch: first channel number that can be used
+ * @max_xfer_size: maximum transfer size per dma descriptor
+ */
+struct mic_dma_device {
+	struct mic_dma_chan mic_ch[MIC_DMA_MAX_NUM_CHAN];
+	struct dma_device dma_dev;
+	struct mbus_device *mbdev;
+	void __iomem *mmio;
+	struct dentry *dbg_dir;
+	int start_ch;
+	size_t max_xfer_size;
+};
+
+static inline struct mic_dma_chan *to_mic_dma_chan(struct dma_chan *ch)
+{
+	return container_of(ch, struct mic_dma_chan, api_ch);
+}
+
+static inline struct mic_dma_device *to_mic_dma_dev(struct mic_dma_chan *ch)
+{
+	return
+	container_of((const typeof(((struct mic_dma_device *)0)->mic_ch)*)
+		     (ch - ch->ch_num), struct mic_dma_device, mic_ch);
+}
+
+static inline struct mbus_device *to_mbus_device(struct mic_dma_chan *ch)
+{
+	return to_mic_dma_dev(ch)->mbdev;
+}
+
+static inline struct mbus_hw_ops *to_mbus_hw_ops(struct mic_dma_chan *ch)
+{
+	return to_mbus_device(ch)->hw_ops;
+}
+
+static inline struct device *mic_dma_ch_to_device(struct mic_dma_chan *ch)
+{
+	return to_mic_dma_dev(ch)->dma_dev.dev;
+}
+
+static inline void __iomem *mic_dma_chan_to_mmio(struct mic_dma_chan *ch)
+{
+	return to_mic_dma_dev(ch)->mmio;
+}
+
+static inline u32 mic_dma_read_reg(struct mic_dma_chan *ch, u32 reg)
+{
+	return ioread32(mic_dma_chan_to_mmio(ch) + MIC_DMA_SBOX_CH_BASE +
+			ch->ch_num * MIC_DMA_SBOX_CHAN_OFF + reg);
+}
+
+static inline void mic_dma_write_reg(struct mic_dma_chan *ch, u32 reg, u32 val)
+{
+	iowrite32(val, mic_dma_chan_to_mmio(ch) + MIC_DMA_SBOX_CH_BASE +
+		  ch->ch_num * MIC_DMA_SBOX_CHAN_OFF + reg);
+}
+
+static inline u32 mic_dma_mmio_read(struct mic_dma_chan *ch, u32 offset)
+{
+	return ioread32(mic_dma_chan_to_mmio(ch) + offset);
+}
+
+static inline void mic_dma_mmio_write(struct mic_dma_chan *ch, u32 val,
+				      u32 offset)
+{
+	iowrite32(val, mic_dma_chan_to_mmio(ch) + offset);
+}
+
+static inline u32 mic_dma_read_cmp_cnt(struct mic_dma_chan *ch)
+{
+	return mic_dma_read_reg(ch, MIC_DMA_REG_DSTAT) &
+	       MIC_DMA_HW_CMP_CNT_MASK;
+}
+
+static inline void mic_dma_chan_set_owner(struct mic_dma_chan *ch)
+{
+	u32 dcr = mic_dma_mmio_read(ch, MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR);
+	u32 chan_num = ch->ch_num;
+
+	dcr = (dcr & ~(0x1 << (chan_num * 2))) | (ch->owner << (chan_num * 2));
+	mic_dma_mmio_write(ch, dcr, MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR);
+}
+
+static inline void mic_dma_enable_chan(struct mic_dma_chan *ch)
+{
+	u32 dcr = mic_dma_mmio_read(ch, MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR);
+
+	dcr |= 2 << (ch->ch_num << 1);
+	mic_dma_mmio_write(ch, dcr, MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR);
+}
+
+static inline void mic_dma_disable_chan(struct mic_dma_chan *ch)
+{
+	u32 dcr = mic_dma_mmio_read(ch, MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR);
+
+	dcr &= ~(2 << (ch->ch_num << 1));
+	mic_dma_mmio_write(ch, dcr, MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR);
+}
+
+static void mic_dma_chan_set_desc_ring(struct mic_dma_chan *ch)
+{
+	u32 drar_hi;
+	dma_addr_t desc_ring_micpa = ch->desc_ring_micpa;
+
+	drar_hi = (MIC_DMA_DESC_RX_SIZE & 0x1ffff) << 4;
+	if (MIC_DMA_CHAN_MIC == ch->owner) {
+		drar_hi |= (desc_ring_micpa >> 32) & 0xf;
+	} else {
+		drar_hi |= MIC_DMA_SBOX_DRARHI_SYS_MASK;
+		drar_hi |= ((desc_ring_micpa >> 34)
+			    & 0x1f) << 21;
+		drar_hi |= (desc_ring_micpa >> 32) & 0x3;
+	}
+	mic_dma_write_reg(ch, MIC_DMA_REG_DRAR_LO, (u32) desc_ring_micpa);
+	mic_dma_write_reg(ch, MIC_DMA_REG_DRAR_HI, drar_hi);
+}
+
+static inline void mic_dma_chan_mask_intr(struct mic_dma_chan *ch)
+{
+	u32 dcar = mic_dma_read_reg(ch, MIC_DMA_REG_DCAR);
+
+	if (MIC_DMA_CHAN_MIC == ch->owner)
+		dcar |= MIC_DMA_SBOX_DCAR_IM0;
+	else
+		dcar |= MIC_DMA_SBOX_DCAR_IM1;
+	mic_dma_write_reg(ch, MIC_DMA_REG_DCAR, dcar);
+}
+
+static inline void mic_dma_chan_unmask_intr(struct mic_dma_chan *ch)
+{
+	u32 dcar = mic_dma_read_reg(ch, MIC_DMA_REG_DCAR);
+
+	if (MIC_DMA_CHAN_MIC == ch->owner)
+		dcar &= ~MIC_DMA_SBOX_DCAR_IM0;
+	else
+		dcar &= ~MIC_DMA_SBOX_DCAR_IM1;
+	mic_dma_write_reg(ch, MIC_DMA_REG_DCAR, dcar);
+}
+
+static void mic_dma_ack_interrupt(struct mic_dma_chan *ch)
+{
+	if (MIC_DMA_CHAN_MIC == ch->owner) {
+		/* HW errata */
+		mic_dma_chan_mask_intr(ch);
+		mic_dma_chan_unmask_intr(ch);
+	}
+	to_mbus_hw_ops(ch)->ack_interrupt(to_mbus_device(ch), ch->ch_num);
+}
+#endif