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/*
* Copyright (C) 2010 NVIDIA Corporation.
* Copyright (C) 2010 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* 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.
*
*/
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/mutex.h>
#include "apbio.h"
#include "iomap.h"
#if defined(CONFIG_TEGRA20_APB_DMA)
static DEFINE_MUTEX(tegra_apb_dma_lock);
static u32 *tegra_apb_bb;
static dma_addr_t tegra_apb_bb_phys;
static DECLARE_COMPLETION(tegra_apb_wait);
static u32 tegra_apb_readl_direct(unsigned long offset);
static void tegra_apb_writel_direct(u32 value, unsigned long offset);
static struct dma_chan *tegra_apb_dma_chan;
static struct dma_slave_config dma_sconfig;
static bool tegra_apb_dma_init(void)
{
dma_cap_mask_t mask;
mutex_lock(&tegra_apb_dma_lock);
/* Check to see if we raced to setup */
if (tegra_apb_dma_chan)
goto skip_init;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
tegra_apb_dma_chan = dma_request_channel(mask, NULL, NULL);
if (!tegra_apb_dma_chan) {
/*
* This is common until the device is probed, so don't
* shout about it.
*/
pr_debug("%s: can not allocate dma channel\n", __func__);
goto err_dma_alloc;
}
tegra_apb_bb = dma_alloc_coherent(NULL, sizeof(u32),
&tegra_apb_bb_phys, GFP_KERNEL);
if (!tegra_apb_bb) {
pr_err("%s: can not allocate bounce buffer\n", __func__);
goto err_buff_alloc;
}
dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
dma_sconfig.src_maxburst = 1;
dma_sconfig.dst_maxburst = 1;
skip_init:
mutex_unlock(&tegra_apb_dma_lock);
return true;
err_buff_alloc:
dma_release_channel(tegra_apb_dma_chan);
tegra_apb_dma_chan = NULL;
err_dma_alloc:
mutex_unlock(&tegra_apb_dma_lock);
return false;
}
static void apb_dma_complete(void *args)
{
complete(&tegra_apb_wait);
}
static int do_dma_transfer(unsigned long apb_add,
enum dma_transfer_direction dir)
{
struct dma_async_tx_descriptor *dma_desc;
int ret;
if (dir == DMA_DEV_TO_MEM)
dma_sconfig.src_addr = apb_add;
else
dma_sconfig.dst_addr = apb_add;
ret = dmaengine_slave_config(tegra_apb_dma_chan, &dma_sconfig);
if (ret)
return ret;
dma_desc = dmaengine_prep_slave_single(tegra_apb_dma_chan,
tegra_apb_bb_phys, sizeof(u32), dir,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!dma_desc)
return -EINVAL;
dma_desc->callback = apb_dma_complete;
dma_desc->callback_param = NULL;
reinit_completion(&tegra_apb_wait);
dmaengine_submit(dma_desc);
dma_async_issue_pending(tegra_apb_dma_chan);
ret = wait_for_completion_timeout(&tegra_apb_wait,
msecs_to_jiffies(50));
if (WARN(ret == 0, "apb read dma timed out")) {
dmaengine_terminate_all(tegra_apb_dma_chan);
return -EFAULT;
}
return 0;
}
static u32 tegra_apb_readl_using_dma(unsigned long offset)
{
int ret;
if (!tegra_apb_dma_chan && !tegra_apb_dma_init())
return tegra_apb_readl_direct(offset);
mutex_lock(&tegra_apb_dma_lock);
ret = do_dma_transfer(offset, DMA_DEV_TO_MEM);
if (ret < 0) {
pr_err("error in reading offset 0x%08lx using dma\n", offset);
*(u32 *)tegra_apb_bb = 0;
}
mutex_unlock(&tegra_apb_dma_lock);
return *((u32 *)tegra_apb_bb);
}
static void tegra_apb_writel_using_dma(u32 value, unsigned long offset)
{
int ret;
if (!tegra_apb_dma_chan && !tegra_apb_dma_init()) {
tegra_apb_writel_direct(value, offset);
return;
}
mutex_lock(&tegra_apb_dma_lock);
*((u32 *)tegra_apb_bb) = value;
ret = do_dma_transfer(offset, DMA_MEM_TO_DEV);
if (ret < 0)
pr_err("error in writing offset 0x%08lx using dma\n", offset);
mutex_unlock(&tegra_apb_dma_lock);
}
#else
#define tegra_apb_readl_using_dma tegra_apb_readl_direct
#define tegra_apb_writel_using_dma tegra_apb_writel_direct
#endif
typedef u32 (*apbio_read_fptr)(unsigned long offset);
typedef void (*apbio_write_fptr)(u32 value, unsigned long offset);
static apbio_read_fptr apbio_read;
static apbio_write_fptr apbio_write;
static u32 tegra_apb_readl_direct(unsigned long offset)
{
return readl(IO_ADDRESS(offset));
}
static void tegra_apb_writel_direct(u32 value, unsigned long offset)
{
writel(value, IO_ADDRESS(offset));
}
void tegra_apb_io_init(void)
{
/* Need to use dma only when it is Tegra20 based platform */
if (of_machine_is_compatible("nvidia,tegra20") ||
!of_have_populated_dt()) {
apbio_read = tegra_apb_readl_using_dma;
apbio_write = tegra_apb_writel_using_dma;
} else {
apbio_read = tegra_apb_readl_direct;
apbio_write = tegra_apb_writel_direct;
}
}
u32 tegra_apb_readl(unsigned long offset)
{
return apbio_read(offset);
}
void tegra_apb_writel(u32 value, unsigned long offset)
{
apbio_write(value, offset);
}
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