dmaengine: add a driver for Intel integrated DMA 64-bit

Intel integrated DMA (iDMA) 64-bit is a specific IP that is used as a part of
LPSS devices such as HSUART or SPI. The iDMA IP is attached for private
usage on each host controller independently.

While it has similarities with Synopsys DesignWare DMA, the following
distinctions doesn't allow to use the existing driver:
- 64-bit mode with corresponding changes in Hardware Linked List data structure
- many slight differences in the channel registers

Moreover this driver is based on the DMA virtual channels framework that helps
to make the driver cleaner and easy to understand.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/dma/Kconfig

@@ -85,6 +85,14 @@ config INTEL_IOP_ADMA
 	help
 	  Enable support for the Intel(R) IOP Series RAID engines.
 
+config IDMA64
+	tristate "Intel integrated DMA 64-bit support"
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable DMA support for Intel Low Power Subsystem such as found on
+	  Intel Skylake PCH.
+
 source "drivers/dma/dw/Kconfig"
 
 config AT_HDMAC

drivers/dma/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_HSU_DMA) += hsu/
 obj-$(CONFIG_MPC512X_DMA) += mpc512x_dma.o
 obj-$(CONFIG_PPC_BESTCOMM) += bestcomm/
 obj-$(CONFIG_MV_XOR) += mv_xor.o
+obj-$(CONFIG_IDMA64) += idma64.o
 obj-$(CONFIG_DW_DMAC_CORE) += dw/
 obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
 obj-$(CONFIG_AT_XDMAC) += at_xdmac.o

drivers/dma/idma64.h

+/*
+ * Driver for the Intel integrated DMA 64-bit
+ *
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef __DMA_IDMA64_H__
+#define __DMA_IDMA64_H__
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "virt-dma.h"
+
+/* Channel registers */
+
+#define IDMA64_CH_SAR		0x00	/* Source Address Register */
+#define IDMA64_CH_DAR		0x08	/* Destination Address Register */
+#define IDMA64_CH_LLP		0x10	/* Linked List Pointer */
+#define IDMA64_CH_CTL_LO	0x18	/* Control Register Low */
+#define IDMA64_CH_CTL_HI	0x1c	/* Control Register High */
+#define IDMA64_CH_SSTAT		0x20
+#define IDMA64_CH_DSTAT		0x28
+#define IDMA64_CH_SSTATAR	0x30
+#define IDMA64_CH_DSTATAR	0x38
+#define IDMA64_CH_CFG_LO	0x40	/* Configuration Register Low */
+#define IDMA64_CH_CFG_HI	0x44	/* Configuration Register High */
+#define IDMA64_CH_SGR		0x48
+#define IDMA64_CH_DSR		0x50
+
+#define IDMA64_CH_LENGTH	0x58
+
+/* Bitfields in CTL_LO */
+#define IDMA64C_CTLL_INT_EN		(1 << 0)	/* irqs enabled? */
+#define IDMA64C_CTLL_DST_WIDTH(x)	((x) << 1)	/* bytes per element */
+#define IDMA64C_CTLL_SRC_WIDTH(x)	((x) << 4)
+#define IDMA64C_CTLL_DST_INC		(0 << 8)	/* DAR update/not */
+#define IDMA64C_CTLL_DST_FIX		(1 << 8)
+#define IDMA64C_CTLL_SRC_INC		(0 << 10)	/* SAR update/not */
+#define IDMA64C_CTLL_SRC_FIX		(1 << 10)
+#define IDMA64C_CTLL_DST_MSIZE(x)	((x) << 11)	/* burst, #elements */
+#define IDMA64C_CTLL_SRC_MSIZE(x)	((x) << 14)
+#define IDMA64C_CTLL_FC_M2P		(1 << 20)	/* mem-to-periph */
+#define IDMA64C_CTLL_FC_P2M		(2 << 20)	/* periph-to-mem */
+#define IDMA64C_CTLL_LLP_D_EN		(1 << 27)	/* dest block chain */
+#define IDMA64C_CTLL_LLP_S_EN		(1 << 28)	/* src block chain */
+
+/* Bitfields in CTL_HI */
+#define IDMA64C_CTLH_BLOCK_TS(x)	((x) & ((1 << 17) - 1))
+#define IDMA64C_CTLH_DONE		(1 << 17)
+
+/* Bitfields in CFG_LO */
+#define IDMA64C_CFGL_DST_BURST_ALIGN	(1 << 0)	/* dst burst align */
+#define IDMA64C_CFGL_SRC_BURST_ALIGN	(1 << 1)	/* src burst align */
+#define IDMA64C_CFGL_CH_SUSP		(1 << 8)
+#define IDMA64C_CFGL_FIFO_EMPTY		(1 << 9)
+#define IDMA64C_CFGL_CH_DRAIN		(1 << 10)	/* drain FIFO */
+#define IDMA64C_CFGL_DST_OPT_BL		(1 << 20)	/* optimize dst burst length */
+#define IDMA64C_CFGL_SRC_OPT_BL		(1 << 21)	/* optimize src burst length */
+
+/* Bitfields in CFG_HI */
+#define IDMA64C_CFGH_SRC_PER(x)		((x) << 0)	/* src peripheral */
+#define IDMA64C_CFGH_DST_PER(x)		((x) << 4)	/* dst peripheral */
+#define IDMA64C_CFGH_RD_ISSUE_THD(x)	((x) << 8)
+#define IDMA64C_CFGH_RW_ISSUE_THD(x)	((x) << 18)
+
+/* Interrupt registers */
+
+#define IDMA64_INT_XFER		0x00
+#define IDMA64_INT_BLOCK	0x08
+#define IDMA64_INT_SRC_TRAN	0x10
+#define IDMA64_INT_DST_TRAN	0x18
+#define IDMA64_INT_ERROR	0x20
+
+#define IDMA64_RAW(x)		(0x2c0 + IDMA64_INT_##x)	/* r */
+#define IDMA64_STATUS(x)	(0x2e8 + IDMA64_INT_##x)	/* r (raw & mask) */
+#define IDMA64_MASK(x)		(0x310 + IDMA64_INT_##x)	/* rw (set = irq enabled) */
+#define IDMA64_CLEAR(x)		(0x338 + IDMA64_INT_##x)	/* w (ack, affects "raw") */
+
+/* Common registers */
+
+#define IDMA64_STATUS_INT	0x360	/* r */
+#define IDMA64_CFG		0x398
+#define IDMA64_CH_EN		0x3a0
+
+/* Bitfields in CFG */
+#define IDMA64_CFG_DMA_EN		(1 << 0)
+
+/* Hardware descriptor for Linked LIst transfers */
+struct idma64_lli {
+	u64		sar;
+	u64		dar;
+	u64		llp;
+	u32		ctllo;
+	u32		ctlhi;
+	u32		sstat;
+	u32		dstat;
+};
+
+struct idma64_hw_desc {
+	struct idma64_lli *lli;
+	dma_addr_t llp;
+	dma_addr_t phys;
+	unsigned int len;
+};
+
+struct idma64_desc {
+	struct virt_dma_desc vdesc;
+	enum dma_transfer_direction direction;
+	struct idma64_hw_desc *hw;
+	unsigned int ndesc;
+	size_t length;
+	enum dma_status status;
+};
+
+static inline struct idma64_desc *to_idma64_desc(struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct idma64_desc, vdesc);
+}
+
+struct idma64_chan {
+	struct virt_dma_chan vchan;
+
+	void __iomem *regs;
+
+	/* hardware configuration */
+	enum dma_transfer_direction direction;
+	unsigned int mask;
+	struct dma_slave_config config;
+
+	void *pool;
+	struct idma64_desc *desc;
+};
+
+static inline struct idma64_chan *to_idma64_chan(struct dma_chan *chan)
+{
+	return container_of(chan, struct idma64_chan, vchan.chan);
+}
+
+#define channel_set_bit(idma64, reg, mask)	\
+	dma_writel(idma64, reg, ((mask) << 8) | (mask))
+#define channel_clear_bit(idma64, reg, mask)	\
+	dma_writel(idma64, reg, ((mask) << 8) | 0)
+
+static inline u32 idma64c_readl(struct idma64_chan *idma64c, int offset)
+{
+	return readl(idma64c->regs + offset);
+}
+
+static inline void idma64c_writel(struct idma64_chan *idma64c, int offset,
+				  u32 value)
+{
+	writel(value, idma64c->regs + offset);
+}
+
+#define channel_readl(idma64c, reg)		\
+	idma64c_readl(idma64c, IDMA64_CH_##reg)
+#define channel_writel(idma64c, reg, value)	\
+	idma64c_writel(idma64c, IDMA64_CH_##reg, (value))
+
+static inline u64 idma64c_readq(struct idma64_chan *idma64c, int offset)
+{
+	u64 l, h;
+
+	l = idma64c_readl(idma64c, offset);
+	h = idma64c_readl(idma64c, offset + 4);
+
+	return l | (h << 32);
+}
+
+static inline void idma64c_writeq(struct idma64_chan *idma64c, int offset,
+				  u64 value)
+{
+	idma64c_writel(idma64c, offset, value);
+	idma64c_writel(idma64c, offset + 4, value >> 32);
+}
+
+#define channel_readq(idma64c, reg)		\
+	idma64c_readq(idma64c, IDMA64_CH_##reg)
+#define channel_writeq(idma64c, reg, value)	\
+	idma64c_writeq(idma64c, IDMA64_CH_##reg, (value))
+
+struct idma64 {
+	struct dma_device dma;
+
+	void __iomem *regs;
+
+	/* channels */
+	unsigned short all_chan_mask;
+	struct idma64_chan *chan;
+};
+
+static inline struct idma64 *to_idma64(struct dma_device *ddev)
+{
+	return container_of(ddev, struct idma64, dma);
+}
+
+static inline u32 idma64_readl(struct idma64 *idma64, int offset)
+{
+	return readl(idma64->regs + offset);
+}
+
+static inline void idma64_writel(struct idma64 *idma64, int offset, u32 value)
+{
+	writel(value, idma64->regs + offset);
+}
+
+#define dma_readl(idma64, reg)			\
+	idma64_readl(idma64, IDMA64_##reg)
+#define dma_writel(idma64, reg, value)		\
+	idma64_writel(idma64, IDMA64_##reg, (value))
+
+/**
+ * struct idma64_chip - representation of DesignWare DMA controller hardware
+ * @dev:		struct device of the DMA controller
+ * @irq:		irq line
+ * @regs:		memory mapped I/O space
+ * @idma64:		struct idma64 that is filed by idma64_probe()
+ */
+struct idma64_chip {
+	struct device	*dev;
+	int		irq;
+	void __iomem	*regs;
+	struct idma64	*idma64;
+};
+
+#endif /* __DMA_IDMA64_H__ */