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openwrtv4/target/linux/brcm2708/patches-4.4/0393-Revert-dmaengine-bcm2835-Add-slave-dma-support.patch
Álvaro Fernández Rojas 20402106a3 brcm2708: update linux 4.4 patches to latest version 
As usual these patches were extracted and rebased from the raspberry pi repo:
https://github.com/raspberrypi/linux/tree/rpi-4.4.y

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2016-07-09 16:29:18 +02:00

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From c748f44b0b10023e4207cb288ce9c169e390fbaf Mon Sep 17 00:00:00 2001
From: Martin Sperl <kernel@martin.sperl.org>
Date: Fri, 22 Apr 2016 17:17:37 +0000
Subject: [PATCH 393/423] Revert "dmaengine: bcm2835: Add slave dma support"
This reverts commit 8a349301238aabb40c9da5ca8c8492b6b8d146f6.
---
drivers/dma/bcm2835-dma.c | 206 ++++------------------------------------------
1 file changed, 14 insertions(+), 192 deletions(-)
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -1,10 +1,11 @@
/*
* BCM2835 DMA engine support
*
+ * This driver only supports cyclic DMA transfers
+ * as needed for the I2S module.
+ *
* Author: Florian Meier <florian.meier@koalo.de>
* Copyright 2013
- * Gellert Weisz <gellert@raspberrypi.org>
- * Copyright 2013-2014
*
* Based on
* OMAP DMAengine support by Russell King
@@ -94,8 +95,6 @@ struct bcm2835_desc {
size_t size;
};
-#define BCM2835_DMA_WAIT_CYCLES 0 /* Slow down DMA transfers: 0-31 */
-
#define BCM2835_DMA_CS 0x00
#define BCM2835_DMA_ADDR 0x04
#define BCM2835_DMA_SOURCE_AD 0x0c
@@ -112,16 +111,12 @@ struct bcm2835_desc {
#define BCM2835_DMA_RESET BIT(31) /* WO, self clearing */
#define BCM2835_DMA_INT_EN BIT(0)
-#define BCM2835_DMA_WAIT_RESP BIT(3)
#define BCM2835_DMA_D_INC BIT(4)
-#define BCM2835_DMA_D_WIDTH BIT(5)
#define BCM2835_DMA_D_DREQ BIT(6)
#define BCM2835_DMA_S_INC BIT(8)
-#define BCM2835_DMA_S_WIDTH BIT(9)
#define BCM2835_DMA_S_DREQ BIT(10)
#define BCM2835_DMA_PER_MAP(x) ((x) << 16)
-#define BCM2835_DMA_WAITS(x) (((x) & 0x1f) << 21)
#define BCM2835_DMA_DATA_TYPE_S8 1
#define BCM2835_DMA_DATA_TYPE_S16 2
@@ -135,14 +130,6 @@ struct bcm2835_desc {
#define BCM2835_DMA_CHAN(n) ((n) << 8) /* Base address */
#define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n))
-#define MAX_NORMAL_TRANSFER SZ_1G
-/*
- * Max length on a Lite channel is 65535 bytes.
- * DMA handles byte-enables on SDRAM reads and writes even on 128-bit accesses,
- * but byte-enables don't exist on peripheral addresses, so align to 32-bit.
- */
-#define MAX_LITE_TRANSFER (SZ_64K - 4)
-
static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
{
return container_of(d, struct bcm2835_dmadev, ddev);
@@ -239,19 +226,13 @@ static irqreturn_t bcm2835_dma_callback(
d = c->desc;
if (d) {
- if (c->cyclic) {
- vchan_cyclic_callback(&d->vd);
-
- /* Keep the DMA engine running */
- writel(BCM2835_DMA_ACTIVE,
- c->chan_base + BCM2835_DMA_CS);
-
- } else {
- vchan_cookie_complete(&c->desc->vd);
- bcm2835_dma_start_desc(c);
- }
+ /* TODO Only works for cyclic DMA */
+ vchan_cyclic_callback(&d->vd);
}
+ /* Keep the DMA engine running */
+ writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
+
spin_unlock_irqrestore(&c->vc.lock, flags);
return IRQ_HANDLED;
@@ -358,6 +339,8 @@ static void bcm2835_dma_issue_pending(st
struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
unsigned long flags;
+ c->cyclic = true; /* Nothing else is implemented */
+
spin_lock_irqsave(&c->vc.lock, flags);
if (vchan_issue_pending(&c->vc) && !c->desc)
bcm2835_dma_start_desc(c);
@@ -375,7 +358,7 @@ static struct dma_async_tx_descriptor *b
struct bcm2835_desc *d;
dma_addr_t dev_addr;
unsigned int es, sync_type;
- unsigned int frame, max_size;
+ unsigned int frame;
int i;
/* Grab configuration */
@@ -410,12 +393,7 @@ static struct dma_async_tx_descriptor *b
d->c = c;
d->dir = direction;
- if (c->ch >= 8) /* LITE channel */
- max_size = MAX_LITE_TRANSFER;
- else
- max_size = MAX_NORMAL_TRANSFER;
- period_len = min(period_len, max_size);
- d->frames = (buf_len - 1) / (period_len + 1);
+ d->frames = buf_len / period_len;
d->cb_list = kcalloc(d->frames, sizeof(*d->cb_list), GFP_KERNEL);
if (!d->cb_list) {
@@ -463,171 +441,17 @@ static struct dma_async_tx_descriptor *b
BCM2835_DMA_PER_MAP(c->dreq);
/* Length of a frame */
- if (frame != d->frames - 1)
- control_block->length = period_len;
- else
- control_block->length = buf_len - (d->frames - 1) *
- period_len;
+ control_block->length = period_len;
d->size += control_block->length;
/*
* Next block is the next frame.
- * This function is called on cyclic DMA transfers.
+ * This DMA engine driver currently only supports cyclic DMA.
* Therefore, wrap around at number of frames.
*/
control_block->next = d->cb_list[((frame + 1) % d->frames)].paddr;
}
- c->cyclic = true;
-
- return vchan_tx_prep(&c->vc, &d->vd, flags);
-}
-
-static struct dma_async_tx_descriptor *
-bcm2835_dma_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 bcm2835_chan *c = to_bcm2835_dma_chan(chan);
- enum dma_slave_buswidth dev_width;
- struct bcm2835_desc *d;
- dma_addr_t dev_addr;
- struct scatterlist *sgent;
- unsigned int i, sync_type, split_cnt, max_size;
-
- if (!is_slave_direction(direction)) {
- dev_err(chan->device->dev, "direction not supported\n");
- return NULL;
- }
-
- if (direction == DMA_DEV_TO_MEM) {
- dev_addr = c->cfg.src_addr;
- dev_width = c->cfg.src_addr_width;
- sync_type = BCM2835_DMA_S_DREQ;
- } else {
- dev_addr = c->cfg.dst_addr;
- dev_width = c->cfg.dst_addr_width;
- sync_type = BCM2835_DMA_D_DREQ;
- }
-
- /* Bus width translates to the element size (ES) */
- switch (dev_width) {
- case DMA_SLAVE_BUSWIDTH_4_BYTES:
- break;
- default:
- dev_err(chan->device->dev, "buswidth not supported: %i\n",
- dev_width);
- return NULL;
- }
-
- /* Allocate and setup the descriptor. */
- d = kzalloc(sizeof(*d), GFP_NOWAIT);
- if (!d)
- return NULL;
-
- d->dir = direction;
-
- if (c->ch >= 8) /* LITE channel */
- max_size = MAX_LITE_TRANSFER;
- else
- max_size = MAX_NORMAL_TRANSFER;
-
- /*
- * Store the length of the SG list in d->frames
- * taking care to account for splitting up transfers
- * too large for a LITE channel
- */
- d->frames = 0;
- for_each_sg(sgl, sgent, sg_len, i) {
- unsigned int len = sg_dma_len(sgent);
-
- d->frames += len / max_size + 1;
- }
-
- /* Allocate memory for control blocks */
- d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb);
- d->control_block_base = dma_zalloc_coherent(chan->device->dev,
- d->control_block_size, &d->control_block_base_phys,
- GFP_NOWAIT);
- if (!d->control_block_base) {
- kfree(d);
- return NULL;
- }
-
- /*
- * Iterate over all SG entries, create a control block
- * for each frame and link them together.
- * Count the number of times an SG entry had to be split
- * as a result of using a LITE channel
- */
- split_cnt = 0;
-
- for_each_sg(sgl, sgent, sg_len, i) {
- unsigned int j;
- dma_addr_t addr = sg_dma_address(sgent);
- unsigned int len = sg_dma_len(sgent);
-
- for (j = 0; j < len; j += max_size) {
- struct bcm2835_dma_cb *control_block =
- &d->control_block_base[i + split_cnt];
-
- /* Setup addresses */
- if (d->dir == DMA_DEV_TO_MEM) {
- control_block->info = BCM2835_DMA_D_INC |
- BCM2835_DMA_D_WIDTH |
- BCM2835_DMA_S_DREQ;
- control_block->src = dev_addr;
- control_block->dst = addr + (dma_addr_t)j;
- } else {
- control_block->info = BCM2835_DMA_S_INC |
- BCM2835_DMA_S_WIDTH |
- BCM2835_DMA_D_DREQ;
- control_block->src = addr + (dma_addr_t)j;
- control_block->dst = dev_addr;
- }
-
- /* Common part */
- control_block->info |=
- BCM2835_DMA_WAITS(BCM2835_DMA_WAIT_CYCLES);
- control_block->info |= BCM2835_DMA_WAIT_RESP;
-
- /* Enable */
- if (i == sg_len - 1 && len - j <= max_size)
- control_block->info |= BCM2835_DMA_INT_EN;
-
- /* Setup synchronization */
- if (sync_type)
- control_block->info |= sync_type;
-
- /* Setup DREQ channel */
- if (c->dreq)
- control_block->info |=
- BCM2835_DMA_PER_MAP(c->dreq);
-
- /* Length of a frame */
- control_block->length = min(len - j, max_size);
- d->size += control_block->length;
-
- if (i < sg_len - 1 || len - j > max_size) {
- /* Next block is the next frame. */
- control_block->next =
- d->control_block_base_phys +
- sizeof(struct bcm2835_dma_cb) *
- (i + split_cnt + 1);
- } else {
- /* Next block is empty. */
- control_block->next = 0;
- }
-
- if (len - j > max_size)
- split_cnt++;
- }
- }
-
- c->cyclic = false;
-
return vchan_tx_prep(&c->vc, &d->vd, flags);
error_cb:
i--;
@@ -796,7 +620,6 @@ static int bcm2835_dma_probe(struct plat
od->ddev.device_tx_status = bcm2835_dma_tx_status;
od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
- od->ddev.device_prep_slave_sg = bcm2835_dma_prep_slave_sg;
od->ddev.device_config = bcm2835_dma_slave_config;
od->ddev.device_terminate_all = bcm2835_dma_terminate_all;
od->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
@@ -886,5 +709,4 @@ module_platform_driver(bcm2835_dma_drive
MODULE_ALIAS("platform:bcm2835-dma");
MODULE_DESCRIPTION("BCM2835 DMA engine driver");
MODULE_AUTHOR("Florian Meier <florian.meier@koalo.de>");
-MODULE_AUTHOR("Gellert Weisz <gellert@raspberrypi.org>");
MODULE_LICENSE("GPL v2");
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