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linux/drivers/dma/at_hdmac_regs.h
Gustavo A. R. Silva e05a0b78f3 dmaengine: at_hdmac: Replace zero-length array with flexible-array 
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Ludovic Desroches<ludovic.desroches@microchip.com>
Link: https://lore.kernel.org/r/20200507190038.GA15272@embeddedor
Signed-off-by: Vinod Koul <vkoul@kernel.org>
2020-05-13 20:25:16 +05:30

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Header file for the Atmel AHB DMA Controller driver
*
* Copyright (C) 2008 Atmel Corporation
*/
#ifndef AT_HDMAC_REGS_H
#define AT_HDMAC_REGS_H
#include <linux/platform_data/dma-atmel.h>
#define AT_DMA_MAX_NR_CHANNELS 8
#define AT_DMA_GCFG 0x00 /* Global Configuration Register */
#define AT_DMA_IF_BIGEND(i) (0x1 << (i)) /* AHB-Lite Interface i in Big-endian mode */
#define AT_DMA_ARB_CFG (0x1 << 4) /* Arbiter mode. */
#define AT_DMA_ARB_CFG_FIXED (0x0 << 4)
#define AT_DMA_ARB_CFG_ROUND_ROBIN (0x1 << 4)
#define AT_DMA_EN 0x04 /* Controller Enable Register */
#define AT_DMA_ENABLE (0x1 << 0)
#define AT_DMA_SREQ 0x08 /* Software Single Request Register */
#define AT_DMA_SSREQ(x) (0x1 << ((x) << 1)) /* Request a source single transfer on channel x */
#define AT_DMA_DSREQ(x) (0x1 << (1 + ((x) << 1))) /* Request a destination single transfer on channel x */
#define AT_DMA_CREQ 0x0C /* Software Chunk Transfer Request Register */
#define AT_DMA_SCREQ(x) (0x1 << ((x) << 1)) /* Request a source chunk transfer on channel x */
#define AT_DMA_DCREQ(x) (0x1 << (1 + ((x) << 1))) /* Request a destination chunk transfer on channel x */
#define AT_DMA_LAST 0x10 /* Software Last Transfer Flag Register */
#define AT_DMA_SLAST(x) (0x1 << ((x) << 1)) /* This src rq is last tx of buffer on channel x */
#define AT_DMA_DLAST(x) (0x1 << (1 + ((x) << 1))) /* This dst rq is last tx of buffer on channel x */
#define AT_DMA_SYNC 0x14 /* Request Synchronization Register */
#define AT_DMA_SYR(h) (0x1 << (h)) /* Synchronize handshake line h */
/* Error, Chained Buffer transfer completed and Buffer transfer completed Interrupt registers */
#define AT_DMA_EBCIER 0x18 /* Enable register */
#define AT_DMA_EBCIDR 0x1C /* Disable register */
#define AT_DMA_EBCIMR 0x20 /* Mask Register */
#define AT_DMA_EBCISR 0x24 /* Status Register */
#define AT_DMA_CBTC_OFFSET 8
#define AT_DMA_ERR_OFFSET 16
#define AT_DMA_BTC(x) (0x1 << (x))
#define AT_DMA_CBTC(x) (0x1 << (AT_DMA_CBTC_OFFSET + (x)))
#define AT_DMA_ERR(x) (0x1 << (AT_DMA_ERR_OFFSET + (x)))
#define AT_DMA_CHER 0x28 /* Channel Handler Enable Register */
#define AT_DMA_ENA(x) (0x1 << (x))
#define AT_DMA_SUSP(x) (0x1 << ( 8 + (x)))
#define AT_DMA_KEEP(x) (0x1 << (24 + (x)))
#define AT_DMA_CHDR 0x2C /* Channel Handler Disable Register */
#define AT_DMA_DIS(x) (0x1 << (x))
#define AT_DMA_RES(x) (0x1 << ( 8 + (x)))
#define AT_DMA_CHSR 0x30 /* Channel Handler Status Register */
#define AT_DMA_EMPT(x) (0x1 << (16 + (x)))
#define AT_DMA_STAL(x) (0x1 << (24 + (x)))
#define AT_DMA_CH_REGS_BASE 0x3C /* Channel registers base address */
#define ch_regs(x) (AT_DMA_CH_REGS_BASE + (x) * 0x28) /* Channel x base addr */
/* Hardware register offset for each channel */
#define ATC_SADDR_OFFSET 0x00 /* Source Address Register */
#define ATC_DADDR_OFFSET 0x04 /* Destination Address Register */
#define ATC_DSCR_OFFSET 0x08 /* Descriptor Address Register */
#define ATC_CTRLA_OFFSET 0x0C /* Control A Register */
#define ATC_CTRLB_OFFSET 0x10 /* Control B Register */
#define ATC_CFG_OFFSET 0x14 /* Configuration Register */
#define ATC_SPIP_OFFSET 0x18 /* Src PIP Configuration Register */
#define ATC_DPIP_OFFSET 0x1C /* Dst PIP Configuration Register */
/* Bitfield definitions */
/* Bitfields in DSCR */
#define ATC_DSCR_IF(i) (0x3 & (i)) /* Dsc feched via AHB-Lite Interface i */
/* Bitfields in CTRLA */
#define ATC_BTSIZE_MAX 0xFFFFUL /* Maximum Buffer Transfer Size */
#define ATC_BTSIZE(x) (ATC_BTSIZE_MAX & (x)) /* Buffer Transfer Size */
#define ATC_SCSIZE_MASK (0x7 << 16) /* Source Chunk Transfer Size */
#define ATC_SCSIZE(x) (ATC_SCSIZE_MASK & ((x) << 16))
#define ATC_SCSIZE_1 (0x0 << 16)
#define ATC_SCSIZE_4 (0x1 << 16)
#define ATC_SCSIZE_8 (0x2 << 16)
#define ATC_SCSIZE_16 (0x3 << 16)
#define ATC_SCSIZE_32 (0x4 << 16)
#define ATC_SCSIZE_64 (0x5 << 16)
#define ATC_SCSIZE_128 (0x6 << 16)
#define ATC_SCSIZE_256 (0x7 << 16)
#define ATC_DCSIZE_MASK (0x7 << 20) /* Destination Chunk Transfer Size */
#define ATC_DCSIZE(x) (ATC_DCSIZE_MASK & ((x) << 20))
#define ATC_DCSIZE_1 (0x0 << 20)
#define ATC_DCSIZE_4 (0x1 << 20)
#define ATC_DCSIZE_8 (0x2 << 20)
#define ATC_DCSIZE_16 (0x3 << 20)
#define ATC_DCSIZE_32 (0x4 << 20)
#define ATC_DCSIZE_64 (0x5 << 20)
#define ATC_DCSIZE_128 (0x6 << 20)
#define ATC_DCSIZE_256 (0x7 << 20)
#define ATC_SRC_WIDTH_MASK (0x3 << 24) /* Source Single Transfer Size */
#define ATC_SRC_WIDTH(x) ((x) << 24)
#define ATC_SRC_WIDTH_BYTE (0x0 << 24)
#define ATC_SRC_WIDTH_HALFWORD (0x1 << 24)
#define ATC_SRC_WIDTH_WORD (0x2 << 24)
#define ATC_REG_TO_SRC_WIDTH(r) (((r) >> 24) & 0x3)
#define ATC_DST_WIDTH_MASK (0x3 << 28) /* Destination Single Transfer Size */
#define ATC_DST_WIDTH(x) ((x) << 28)
#define ATC_DST_WIDTH_BYTE (0x0 << 28)
#define ATC_DST_WIDTH_HALFWORD (0x1 << 28)
#define ATC_DST_WIDTH_WORD (0x2 << 28)
#define ATC_DONE (0x1 << 31) /* Tx Done (only written back in descriptor) */
/* Bitfields in CTRLB */
#define ATC_SIF(i) (0x3 & (i)) /* Src tx done via AHB-Lite Interface i */
#define ATC_DIF(i) ((0x3 & (i)) << 4) /* Dst tx done via AHB-Lite Interface i */
/* Specify AHB interfaces */
#define AT_DMA_MEM_IF 0 /* interface 0 as memory interface */
#define AT_DMA_PER_IF 1 /* interface 1 as peripheral interface */
#define ATC_SRC_PIP (0x1 << 8) /* Source Picture-in-Picture enabled */
#define ATC_DST_PIP (0x1 << 12) /* Destination Picture-in-Picture enabled */
#define ATC_SRC_DSCR_DIS (0x1 << 16) /* Src Descriptor fetch disable */
#define ATC_DST_DSCR_DIS (0x1 << 20) /* Dst Descriptor fetch disable */
#define ATC_FC_MASK (0x7 << 21) /* Choose Flow Controller */
#define ATC_FC_MEM2MEM (0x0 << 21) /* Mem-to-Mem (DMA) */
#define ATC_FC_MEM2PER (0x1 << 21) /* Mem-to-Periph (DMA) */
#define ATC_FC_PER2MEM (0x2 << 21) /* Periph-to-Mem (DMA) */
#define ATC_FC_PER2PER (0x3 << 21) /* Periph-to-Periph (DMA) */
#define ATC_FC_PER2MEM_PER (0x4 << 21) /* Periph-to-Mem (Peripheral) */
#define ATC_FC_MEM2PER_PER (0x5 << 21) /* Mem-to-Periph (Peripheral) */
#define ATC_FC_PER2PER_SRCPER (0x6 << 21) /* Periph-to-Periph (Src Peripheral) */
#define ATC_FC_PER2PER_DSTPER (0x7 << 21) /* Periph-to-Periph (Dst Peripheral) */
#define ATC_SRC_ADDR_MODE_MASK (0x3 << 24)
#define ATC_SRC_ADDR_MODE_INCR (0x0 << 24) /* Incrementing Mode */
#define ATC_SRC_ADDR_MODE_DECR (0x1 << 24) /* Decrementing Mode */
#define ATC_SRC_ADDR_MODE_FIXED (0x2 << 24) /* Fixed Mode */
#define ATC_DST_ADDR_MODE_MASK (0x3 << 28)
#define ATC_DST_ADDR_MODE_INCR (0x0 << 28) /* Incrementing Mode */
#define ATC_DST_ADDR_MODE_DECR (0x1 << 28) /* Decrementing Mode */
#define ATC_DST_ADDR_MODE_FIXED (0x2 << 28) /* Fixed Mode */
#define ATC_IEN (0x1 << 30) /* BTC interrupt enable (active low) */
#define ATC_AUTO (0x1 << 31) /* Auto multiple buffer tx enable */
/* Bitfields in CFG */
/* are in at_hdmac.h */
/* Bitfields in SPIP */
#define ATC_SPIP_HOLE(x) (0xFFFFU & (x))
#define ATC_SPIP_BOUNDARY(x) ((0x3FF & (x)) << 16)
/* Bitfields in DPIP */
#define ATC_DPIP_HOLE(x) (0xFFFFU & (x))
#define ATC_DPIP_BOUNDARY(x) ((0x3FF & (x)) << 16)
/*-- descriptors -----------------------------------------------------*/
/* LLI == Linked List Item; aka DMA buffer descriptor */
struct at_lli {
/* values that are not changed by hardware */
dma_addr_t saddr;
dma_addr_t daddr;
/* value that may get written back: */
u32 ctrla;
/* more values that are not changed by hardware */
u32 ctrlb;
dma_addr_t dscr; /* chain to next lli */
};
/**
* struct at_desc - software descriptor
* @at_lli: hardware lli structure
* @txd: support for the async_tx api
* @desc_node: node on the channed descriptors list
* @len: descriptor byte count
* @total_len: total transaction byte count
*/
struct at_desc {
/* FIRST values the hardware uses */
struct at_lli lli;
/* THEN values for driver housekeeping */
struct list_head tx_list;
struct dma_async_tx_descriptor txd;
struct list_head desc_node;
size_t len;
size_t total_len;
/* Interleaved data */
size_t boundary;
size_t dst_hole;
size_t src_hole;
/* Memset temporary buffer */
bool memset_buffer;
dma_addr_t memset_paddr;
int *memset_vaddr;
};
static inline struct at_desc *
txd_to_at_desc(struct dma_async_tx_descriptor *txd)
{
return container_of(txd, struct at_desc, txd);
}
/*-- Channels --------------------------------------------------------*/
/**
* atc_status - information bits stored in channel status flag
*
* Manipulated with atomic operations.
*/
enum atc_status {
ATC_IS_ERROR = 0,
ATC_IS_PAUSED = 1,
ATC_IS_CYCLIC = 24,
};
/**
* struct at_dma_chan - internal representation of an Atmel HDMAC channel
* @chan_common: common dmaengine channel object members
* @device: parent device
* @ch_regs: memory mapped register base
* @mask: channel index in a mask
* @per_if: peripheral interface
* @mem_if: memory interface
* @status: transmit status information from irq/prep* functions
* to tasklet (use atomic operations)
* @tasklet: bottom half to finish transaction work
* @save_cfg: configuration register that is saved on suspend/resume cycle
* @save_dscr: for cyclic operations, preserve next descriptor address in
* the cyclic list on suspend/resume cycle
* @dma_sconfig: configuration for slave transfers, passed via
* .device_config
* @lock: serializes enqueue/dequeue operations to descriptors lists
* @active_list: list of descriptors dmaengine is being running on
* @queue: list of descriptors ready to be submitted to engine
* @free_list: list of descriptors usable by the channel
*/
struct at_dma_chan {
struct dma_chan chan_common;
struct at_dma *device;
void __iomem *ch_regs;
u8 mask;
u8 per_if;
u8 mem_if;
unsigned long status;
struct tasklet_struct tasklet;
u32 save_cfg;
u32 save_dscr;
struct dma_slave_config dma_sconfig;
spinlock_t lock;
/* these other elements are all protected by lock */
struct list_head active_list;
struct list_head queue;
struct list_head free_list;
};
#define channel_readl(atchan, name) \
__raw_readl((atchan)->ch_regs + ATC_##name##_OFFSET)
#define channel_writel(atchan, name, val) \
__raw_writel((val), (atchan)->ch_regs + ATC_##name##_OFFSET)
static inline struct at_dma_chan *to_at_dma_chan(struct dma_chan *dchan)
{
return container_of(dchan, struct at_dma_chan, chan_common);
}
/*
* Fix sconfig's burst size according to at_hdmac. We need to convert them as:
* 1 -> 0, 4 -> 1, 8 -> 2, 16 -> 3, 32 -> 4, 64 -> 5, 128 -> 6, 256 -> 7.
*
* This can be done by finding most significant bit set.
*/
static inline void convert_burst(u32 *maxburst)
{
if (*maxburst > 1)
*maxburst = fls(*maxburst) - 2;
else
*maxburst = 0;
}
/*
* Fix sconfig's bus width according to at_hdmac.
* 1 byte -> 0, 2 bytes -> 1, 4 bytes -> 2.
*/
static inline u8 convert_buswidth(enum dma_slave_buswidth addr_width)
{
switch (addr_width) {
case DMA_SLAVE_BUSWIDTH_2_BYTES:
return 1;
case DMA_SLAVE_BUSWIDTH_4_BYTES:
return 2;
default:
/* For 1 byte width or fallback */
return 0;
}
}
/*-- Controller ------------------------------------------------------*/
/**
* struct at_dma - internal representation of an Atmel HDMA Controller
* @chan_common: common dmaengine dma_device object members
* @atdma_devtype: identifier of DMA controller compatibility
* @ch_regs: memory mapped register base
* @clk: dma controller clock
* @save_imr: interrupt mask register that is saved on suspend/resume cycle
* @all_chan_mask: all channels availlable in a mask
* @dma_desc_pool: base of DMA descriptor region (DMA address)
* @chan: channels table to store at_dma_chan structures
*/
struct at_dma {
struct dma_device dma_common;
void __iomem *regs;
struct clk *clk;
u32 save_imr;
u8 all_chan_mask;
struct dma_pool *dma_desc_pool;
struct dma_pool *memset_pool;
/* AT THE END channels table */
struct at_dma_chan chan[];
};
#define dma_readl(atdma, name) \
__raw_readl((atdma)->regs + AT_DMA_##name)
#define dma_writel(atdma, name, val) \
__raw_writel((val), (atdma)->regs + AT_DMA_##name)
static inline struct at_dma *to_at_dma(struct dma_device *ddev)
{
return container_of(ddev, struct at_dma, dma_common);
}
/*-- Helper functions ------------------------------------------------*/
static struct device *chan2dev(struct dma_chan *chan)
{
return &chan->dev->device;
}
#if defined(VERBOSE_DEBUG)
static void vdbg_dump_regs(struct at_dma_chan *atchan)
{
struct at_dma *atdma = to_at_dma(atchan->chan_common.device);
dev_err(chan2dev(&atchan->chan_common),
" channel %d : imr = 0x%x, chsr = 0x%x\n",
atchan->chan_common.chan_id,
dma_readl(atdma, EBCIMR),
dma_readl(atdma, CHSR));
dev_err(chan2dev(&atchan->chan_common),
" channel: s0x%x d0x%x ctrl0x%x:0x%x cfg0x%x l0x%x\n",
channel_readl(atchan, SADDR),
channel_readl(atchan, DADDR),
channel_readl(atchan, CTRLA),
channel_readl(atchan, CTRLB),
channel_readl(atchan, CFG),
channel_readl(atchan, DSCR));
}
#else
static void vdbg_dump_regs(struct at_dma_chan *atchan) {}
#endif
static void atc_dump_lli(struct at_dma_chan *atchan, struct at_lli *lli)
{
dev_crit(chan2dev(&atchan->chan_common),
"desc: s%pad d%pad ctrl0x%x:0x%x l%pad\n",
&lli->saddr, &lli->daddr,
lli->ctrla, lli->ctrlb, &lli->dscr);
}
static void atc_setup_irq(struct at_dma *atdma, int chan_id, int on)
{
u32 ebci;
/* enable interrupts on buffer transfer completion & error */
ebci = AT_DMA_BTC(chan_id)
| AT_DMA_ERR(chan_id);
if (on)
dma_writel(atdma, EBCIER, ebci);
else
dma_writel(atdma, EBCIDR, ebci);
}
static void atc_enable_chan_irq(struct at_dma *atdma, int chan_id)
{
atc_setup_irq(atdma, chan_id, 1);
}
static void atc_disable_chan_irq(struct at_dma *atdma, int chan_id)
{
atc_setup_irq(atdma, chan_id, 0);
}
/**
* atc_chan_is_enabled - test if given channel is enabled
* @atchan: channel we want to test status
*/
static inline int atc_chan_is_enabled(struct at_dma_chan *atchan)
{
struct at_dma *atdma = to_at_dma(atchan->chan_common.device);
return !!(dma_readl(atdma, CHSR) & atchan->mask);
}
/**
* atc_chan_is_paused - test channel pause/resume status
* @atchan: channel we want to test status
*/
static inline int atc_chan_is_paused(struct at_dma_chan *atchan)
{
return test_bit(ATC_IS_PAUSED, &atchan->status);
}
/**
* atc_chan_is_cyclic - test if given channel has cyclic property set
* @atchan: channel we want to test status
*/
static inline int atc_chan_is_cyclic(struct at_dma_chan *atchan)
{
return test_bit(ATC_IS_CYCLIC, &atchan->status);
}
/**
* set_desc_eol - set end-of-link to descriptor so it will end transfer
* @desc: descriptor, signle or at the end of a chain, to end chain on
*/
static void set_desc_eol(struct at_desc *desc)
{
u32 ctrlb = desc->lli.ctrlb;
ctrlb &= ~ATC_IEN;
ctrlb |= ATC_SRC_DSCR_DIS | ATC_DST_DSCR_DIS;
desc->lli.ctrlb = ctrlb;
desc->lli.dscr = 0;
}
#endif /* AT_HDMAC_REGS_H */
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