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linux/drivers/dma/uniphier-mdmac.c
Gustavo A. R. Silva 6a8785082c dmaengine: uniphier-mdmac: replace zero-length array with flexible-array member 
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]

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 <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200213003535.GA3269@embeddedor.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
2020-02-13 20:15:57 +05:30

502 lines
13 KiB
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// SPDX-License-Identifier: GPL-2.0
//
// Copyright (C) 2018 Socionext Inc.
// Author: Masahiro Yamada <yamada.masahiro@socionext.com>
#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_dma.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>
#include "virt-dma.h"
/* registers common for all channels */
#define UNIPHIER_MDMAC_CMD 0x000 /* issue DMA start/abort */
#define UNIPHIER_MDMAC_CMD_ABORT BIT(31) /* 1: abort, 0: start */
/* per-channel registers */
#define UNIPHIER_MDMAC_CH_OFFSET 0x100
#define UNIPHIER_MDMAC_CH_STRIDE 0x040
#define UNIPHIER_MDMAC_CH_IRQ_STAT 0x010 /* current hw status (RO) */
#define UNIPHIER_MDMAC_CH_IRQ_REQ 0x014 /* latched STAT (WOC) */
#define UNIPHIER_MDMAC_CH_IRQ_EN 0x018 /* IRQ enable mask */
#define UNIPHIER_MDMAC_CH_IRQ_DET 0x01c /* REQ & EN (RO) */
#define UNIPHIER_MDMAC_CH_IRQ__ABORT BIT(13)
#define UNIPHIER_MDMAC_CH_IRQ__DONE BIT(1)
#define UNIPHIER_MDMAC_CH_SRC_MODE 0x020 /* mode of source */
#define UNIPHIER_MDMAC_CH_DEST_MODE 0x024 /* mode of destination */
#define UNIPHIER_MDMAC_CH_MODE__ADDR_INC (0 << 4)
#define UNIPHIER_MDMAC_CH_MODE__ADDR_DEC (1 << 4)
#define UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED (2 << 4)
#define UNIPHIER_MDMAC_CH_SRC_ADDR 0x028 /* source address */
#define UNIPHIER_MDMAC_CH_DEST_ADDR 0x02c /* destination address */
#define UNIPHIER_MDMAC_CH_SIZE 0x030 /* transfer bytes */
#define UNIPHIER_MDMAC_SLAVE_BUSWIDTHS \
(BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
BIT(DMA_SLAVE_BUSWIDTH_3_BYTES) | \
BIT(DMA_SLAVE_BUSWIDTH_4_BYTES))
struct uniphier_mdmac_desc {
struct virt_dma_desc vd;
struct scatterlist *sgl;
unsigned int sg_len;
unsigned int sg_cur;
enum dma_transfer_direction dir;
};
struct uniphier_mdmac_chan {
struct virt_dma_chan vc;
struct uniphier_mdmac_device *mdev;
struct uniphier_mdmac_desc *md;
void __iomem *reg_ch_base;
unsigned int chan_id;
};
struct uniphier_mdmac_device {
struct dma_device ddev;
struct clk *clk;
void __iomem *reg_base;
struct uniphier_mdmac_chan channels[];
};
static struct uniphier_mdmac_chan *
to_uniphier_mdmac_chan(struct virt_dma_chan *vc)
{
return container_of(vc, struct uniphier_mdmac_chan, vc);
}
static struct uniphier_mdmac_desc *
to_uniphier_mdmac_desc(struct virt_dma_desc *vd)
{
return container_of(vd, struct uniphier_mdmac_desc, vd);
}
/* mc->vc.lock must be held by caller */
static struct uniphier_mdmac_desc *
uniphier_mdmac_next_desc(struct uniphier_mdmac_chan *mc)
{
struct virt_dma_desc *vd;
vd = vchan_next_desc(&mc->vc);
if (!vd) {
mc->md = NULL;
return NULL;
}
list_del(&vd->node);
mc->md = to_uniphier_mdmac_desc(vd);
return mc->md;
}
/* mc->vc.lock must be held by caller */
static void uniphier_mdmac_handle(struct uniphier_mdmac_chan *mc,
struct uniphier_mdmac_desc *md)
{
struct uniphier_mdmac_device *mdev = mc->mdev;
struct scatterlist *sg;
u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__DONE;
u32 src_mode, src_addr, dest_mode, dest_addr, chunk_size;
sg = &md->sgl[md->sg_cur];
if (md->dir == DMA_MEM_TO_DEV) {
src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
src_addr = sg_dma_address(sg);
dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
dest_addr = 0;
} else {
src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
src_addr = 0;
dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
dest_addr = sg_dma_address(sg);
}
chunk_size = sg_dma_len(sg);
writel(src_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_MODE);
writel(dest_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_MODE);
writel(src_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_ADDR);
writel(dest_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_ADDR);
writel(chunk_size, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SIZE);
/* write 1 to clear */
writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_EN);
writel(BIT(mc->chan_id), mdev->reg_base + UNIPHIER_MDMAC_CMD);
}
/* mc->vc.lock must be held by caller */
static void uniphier_mdmac_start(struct uniphier_mdmac_chan *mc)
{
struct uniphier_mdmac_desc *md;
md = uniphier_mdmac_next_desc(mc);
if (md)
uniphier_mdmac_handle(mc, md);
}
/* mc->vc.lock must be held by caller */
static int uniphier_mdmac_abort(struct uniphier_mdmac_chan *mc)
{
struct uniphier_mdmac_device *mdev = mc->mdev;
u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__ABORT;
u32 val;
/* write 1 to clear */
writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
writel(UNIPHIER_MDMAC_CMD_ABORT | BIT(mc->chan_id),
mdev->reg_base + UNIPHIER_MDMAC_CMD);
/*
* Abort should be accepted soon. We poll the bit here instead of
* waiting for the interrupt.
*/
return readl_poll_timeout(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ,
val, val & irq_flag, 0, 20);
}
static irqreturn_t uniphier_mdmac_interrupt(int irq, void *dev_id)
{
struct uniphier_mdmac_chan *mc = dev_id;
struct uniphier_mdmac_desc *md;
irqreturn_t ret = IRQ_HANDLED;
u32 irq_stat;
spin_lock(&mc->vc.lock);
irq_stat = readl(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_DET);
/*
* Some channels share a single interrupt line. If the IRQ status is 0,
* this is probably triggered by a different channel.
*/
if (!irq_stat) {
ret = IRQ_NONE;
goto out;
}
/* write 1 to clear */
writel(irq_stat, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
/*
* UNIPHIER_MDMAC_CH_IRQ__DONE interrupt is asserted even when the DMA
* is aborted. To distinguish the normal completion and the abort,
* check mc->md. If it is NULL, we are aborting.
*/
md = mc->md;
if (!md)
goto out;
md->sg_cur++;
if (md->sg_cur >= md->sg_len) {
vchan_cookie_complete(&md->vd);
md = uniphier_mdmac_next_desc(mc);
if (!md)
goto out;
}
uniphier_mdmac_handle(mc, md);
out:
spin_unlock(&mc->vc.lock);
return ret;
}
static void uniphier_mdmac_free_chan_resources(struct dma_chan *chan)
{
vchan_free_chan_resources(to_virt_chan(chan));
}
static struct dma_async_tx_descriptor *
uniphier_mdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len,
enum dma_transfer_direction direction,
unsigned long flags, void *context)
{
struct virt_dma_chan *vc = to_virt_chan(chan);
struct uniphier_mdmac_desc *md;
if (!is_slave_direction(direction))
return NULL;
md = kzalloc(sizeof(*md), GFP_NOWAIT);
if (!md)
return NULL;
md->sgl = sgl;
md->sg_len = sg_len;
md->dir = direction;
return vchan_tx_prep(vc, &md->vd, flags);
}
static int uniphier_mdmac_terminate_all(struct dma_chan *chan)
{
struct virt_dma_chan *vc = to_virt_chan(chan);
struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
unsigned long flags;
int ret = 0;
LIST_HEAD(head);
spin_lock_irqsave(&vc->lock, flags);
if (mc->md) {
vchan_terminate_vdesc(&mc->md->vd);
mc->md = NULL;
ret = uniphier_mdmac_abort(mc);
}
vchan_get_all_descriptors(vc, &head);
spin_unlock_irqrestore(&vc->lock, flags);
vchan_dma_desc_free_list(vc, &head);
return ret;
}
static void uniphier_mdmac_synchronize(struct dma_chan *chan)
{
vchan_synchronize(to_virt_chan(chan));
}
static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
dma_cookie_t cookie,
struct dma_tx_state *txstate)
{
struct virt_dma_chan *vc;
struct virt_dma_desc *vd;
struct uniphier_mdmac_chan *mc;
struct uniphier_mdmac_desc *md = NULL;
enum dma_status stat;
unsigned long flags;
int i;
stat = dma_cookie_status(chan, cookie, txstate);
/* Return immediately if we do not need to compute the residue. */
if (stat == DMA_COMPLETE || !txstate)
return stat;
vc = to_virt_chan(chan);
spin_lock_irqsave(&vc->lock, flags);
mc = to_uniphier_mdmac_chan(vc);
if (mc->md && mc->md->vd.tx.cookie == cookie) {
/* residue from the on-flight chunk */
txstate->residue = readl(mc->reg_ch_base +
UNIPHIER_MDMAC_CH_SIZE);
md = mc->md;
}
if (!md) {
vd = vchan_find_desc(vc, cookie);
if (vd)
md = to_uniphier_mdmac_desc(vd);
}
if (md) {
/* residue from the queued chunks */
for (i = md->sg_cur; i < md->sg_len; i++)
txstate->residue += sg_dma_len(&md->sgl[i]);
}
spin_unlock_irqrestore(&vc->lock, flags);
return stat;
}
static void uniphier_mdmac_issue_pending(struct dma_chan *chan)
{
struct virt_dma_chan *vc = to_virt_chan(chan);
struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
unsigned long flags;
spin_lock_irqsave(&vc->lock, flags);
if (vchan_issue_pending(vc) && !mc->md)
uniphier_mdmac_start(mc);
spin_unlock_irqrestore(&vc->lock, flags);
}
static void uniphier_mdmac_desc_free(struct virt_dma_desc *vd)
{
kfree(to_uniphier_mdmac_desc(vd));
}
static int uniphier_mdmac_chan_init(struct platform_device *pdev,
struct uniphier_mdmac_device *mdev,
int chan_id)
{
struct device *dev = &pdev->dev;
struct uniphier_mdmac_chan *mc = &mdev->channels[chan_id];
char *irq_name;
int irq, ret;
irq = platform_get_irq(pdev, chan_id);
if (irq < 0)
return irq;
irq_name = devm_kasprintf(dev, GFP_KERNEL, "uniphier-mio-dmac-ch%d",
chan_id);
if (!irq_name)
return -ENOMEM;
ret = devm_request_irq(dev, irq, uniphier_mdmac_interrupt,
IRQF_SHARED, irq_name, mc);
if (ret)
return ret;
mc->mdev = mdev;
mc->reg_ch_base = mdev->reg_base + UNIPHIER_MDMAC_CH_OFFSET +
UNIPHIER_MDMAC_CH_STRIDE * chan_id;
mc->chan_id = chan_id;
mc->vc.desc_free = uniphier_mdmac_desc_free;
vchan_init(&mc->vc, &mdev->ddev);
return 0;
}
static int uniphier_mdmac_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct uniphier_mdmac_device *mdev;
struct dma_device *ddev;
int nr_chans, ret, i;
nr_chans = platform_irq_count(pdev);
if (nr_chans < 0)
return nr_chans;
ret = dma_set_mask(dev, DMA_BIT_MASK(32));
if (ret)
return ret;
mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
GFP_KERNEL);
if (!mdev)
return -ENOMEM;
mdev->reg_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(mdev->reg_base))
return PTR_ERR(mdev->reg_base);
mdev->clk = devm_clk_get(dev, NULL);
if (IS_ERR(mdev->clk)) {
dev_err(dev, "failed to get clock\n");
return PTR_ERR(mdev->clk);
}
ret = clk_prepare_enable(mdev->clk);
if (ret)
return ret;
ddev = &mdev->ddev;
ddev->dev = dev;
dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
ddev->src_addr_widths = UNIPHIER_MDMAC_SLAVE_BUSWIDTHS;
ddev->dst_addr_widths = UNIPHIER_MDMAC_SLAVE_BUSWIDTHS;
ddev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
ddev->device_free_chan_resources = uniphier_mdmac_free_chan_resources;
ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
ddev->device_terminate_all = uniphier_mdmac_terminate_all;
ddev->device_synchronize = uniphier_mdmac_synchronize;
ddev->device_tx_status = uniphier_mdmac_tx_status;
ddev->device_issue_pending = uniphier_mdmac_issue_pending;
INIT_LIST_HEAD(&ddev->channels);
for (i = 0; i < nr_chans; i++) {
ret = uniphier_mdmac_chan_init(pdev, mdev, i);
if (ret)
goto disable_clk;
}
ret = dma_async_device_register(ddev);
if (ret)
goto disable_clk;
ret = of_dma_controller_register(dev->of_node, of_dma_xlate_by_chan_id,
ddev);
if (ret)
goto unregister_dmac;
platform_set_drvdata(pdev, mdev);
return 0;
unregister_dmac:
dma_async_device_unregister(ddev);
disable_clk:
clk_disable_unprepare(mdev->clk);
return ret;
}
static int uniphier_mdmac_remove(struct platform_device *pdev)
{
struct uniphier_mdmac_device *mdev = platform_get_drvdata(pdev);
struct dma_chan *chan;
int ret;
/*
* Before reaching here, almost all descriptors have been freed by the
* ->device_free_chan_resources() hook. However, each channel might
* be still holding one descriptor that was on-flight at that moment.
* Terminate it to make sure this hardware is no longer running. Then,
* free the channel resources once again to avoid memory leak.
*/
list_for_each_entry(chan, &mdev->ddev.channels, device_node) {
ret = dmaengine_terminate_sync(chan);
if (ret)
return ret;
uniphier_mdmac_free_chan_resources(chan);
}
of_dma_controller_free(pdev->dev.of_node);
dma_async_device_unregister(&mdev->ddev);
clk_disable_unprepare(mdev->clk);
return 0;
}
static const struct of_device_id uniphier_mdmac_match[] = {
{ .compatible = "socionext,uniphier-mio-dmac" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, uniphier_mdmac_match);
static struct platform_driver uniphier_mdmac_driver = {
.probe = uniphier_mdmac_probe,
.remove = uniphier_mdmac_remove,
.driver = {
.name = "uniphier-mio-dmac",
.of_match_table = uniphier_mdmac_match,
},
};
module_platform_driver(uniphier_mdmac_driver);
MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
MODULE_DESCRIPTION("UniPhier MIO DMAC driver");
MODULE_LICENSE("GPL v2");
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