// SPDX-License-Identifier: GPL-2.0-only
/*
* Device tree helpers for DMA request / controller
*
* Based on of_gpio.c
*
* Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
*/
#include <linux/device.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_dma.h>
#include "dmaengine.h"
static LIST_HEAD(of_dma_list);
static DEFINE_MUTEX(of_dma_lock);
/**
* of_dma_find_controller - Get a DMA controller in DT DMA helpers list
* @dma_spec: pointer to DMA specifier as found in the device tree
*
* Finds a DMA controller with matching device node and number for dma cells
* in a list of registered DMA controllers. If a match is found a valid pointer
* to the DMA data stored is returned. A NULL pointer is returned if no match is
* found.
*/
static struct of_dma *of_dma_find_controller(const struct of_phandle_args *dma_spec)
{
struct of_dma *ofdma;
list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
if (ofdma->of_node == dma_spec->np)
return ofdma;
pr_debug("%s: can't find DMA controller %pOF\n", __func__,
dma_spec->np);
return NULL;
}
/**
* of_dma_router_xlate - translation function for router devices
* @dma_spec: pointer to DMA specifier as found in the device tree
* @ofdma: pointer to DMA controller data (router information)
*
* The function creates new dma_spec to be passed to the router driver's
* of_dma_route_allocate() function to prepare a dma_spec which will be used
* to request channel from the real DMA controller.
*/
static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma)
{
struct dma_chan *chan;
struct of_dma *ofdma_target;
struct of_phandle_args dma_spec_target;
void *route_data;
/* translate the request for the real DMA controller */
memcpy(&dma_spec_target, dma_spec, sizeof(dma_spec_target));
route_data = ofdma->of_dma_route_allocate(&dma_spec_target, ofdma);
if (IS_ERR(route_data))
return NULL;
ofdma_target = of_dma_find_controller(&dma_spec_target);
if (!ofdma_target) {
ofdma->dma_router->route_free(ofdma->dma_router->dev,
route_data);
chan = ERR_PTR(-EPROBE_DEFER);
goto err;
}
chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
if (IS_ERR_OR_NULL(chan)) {
ofdma->dma_router->route_free(ofdma->dma_router->dev,
route_data);
} else {
int ret = 0;
chan->router = ofdma->dma_router;
chan->route_data = route_data;
if (chan->device->device_router_config)
ret = chan->device->device_router_config(chan);
if (ret) {
dma_release_channel(chan);
chan = ERR_PTR(ret);
}
}
err:
/*
* Need to put the node back since the ofdma->of_dma_route_allocate
* has taken it for generating the new, translated dma_spec
*/
of_node_put(dma_spec_target.np);
return chan;
}
/**
* of_dma_controller_register - Register a DMA controller to DT DMA helpers
* @np: device node of DMA controller
* @of_dma_xlate: translation function which converts a phandle
* arguments list into a dma_chan structure
* @data: pointer to controller specific data to be used by
* translation function
*
* Returns 0 on success or appropriate errno value on error.
*
* Allocated memory should be freed with appropriate of_dma_controller_free()
* call.
*/
int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
(struct of_phandle_args *, struct of_dma *),
void *data)
{
struct of_dma *ofdma;
if (!np || !of_dma_xlate) {
pr_err("%s: not enough information provided\n", __func__);
return -EINVAL;
}
ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
if (!ofdma)
return -ENOMEM;
ofdma->of_node = np;
ofdma->of_dma_xlate = of_dma_xlate;
ofdma->of_dma_data = data;
/* Now queue of_dma controller structure in list */
mutex_lock(&of_dma_lock);
list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
mutex_unlock(&of_dma_lock);
return 0;
}
EXPORT_SYMBOL_GPL(of_dma_controller_register);
/**
* of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
* @np: device node of DMA controller
*
* Memory allocated by of_dma_controller_register() is freed here.
*/
void of_dma_controller_free(struct device_node *np)
{
struct of_dma *ofdma;
mutex_lock(&of_dma_lock);
list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
if (ofdma->of_node == np) {
list_del(&ofdma->of_dma_controllers);
kfree(ofdma);
break;
}
mutex_unlock(&of_dma_lock);
}
EXPORT_SYMBOL_GPL(of_dma_controller_free);
/**
* of_dma_router_register - Register a DMA router to DT DMA helpers as a
* controller
* @np: device node of DMA router
* @of_dma_route_allocate: setup function for the router which need to
* modify the dma_spec for the DMA controller to
* use and to set up the requested route.
* @dma_router: pointer to dma_router structure to be used when
* the route need to be free up.
*
* Returns 0 on success or appropriate errno value on error.
*
* Allocated memory should be freed with appropriate of_dma_controller_free()
* call.
*/
int of_dma_router_register(struct device_node *np,
void *(*of_dma_route_allocate)
(struct of_phandle_args *, struct of_dma *),
struct dma_router *dma_router)
{
struct of_dma *ofdma;
if (!np || !of_dma_route_allocate || !dma_router) {
pr_err("%s: not enough information provided\n", __func__);
return -EINVAL;
}
ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
if (!ofdma)
return -ENOMEM;
ofdma->of_node = np;
ofdma->of_dma_xlate = of_dma_router_xlate;
ofdma->of_dma_route_allocate = of_dma_route_allocate;
ofdma->dma_router = dma_router;
/* Now queue of_dma controller structure in list */
mutex_lock(&of_dma_lock);
list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
mutex_unlock(&of_dma_lock);
return 0;
}
EXPORT_SYMBOL_GPL(of_dma_router_register);
/**
* of_dma_match_channel - Check if a DMA specifier matches name
* @np: device node to look for DMA channels
* @name: channel name to be matched
* @index: index of DMA specifier in list of DMA specifiers
* @dma_spec: pointer to DMA specifier as found in the device tree
*
* Check if the DMA specifier pointed to by the index in a list of DMA
* specifiers, matches the name provided. Returns 0 if the name matches and
* a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
*/
static int of_dma_match_channel(struct device_node *np, const char *name,
int index, struct of_phandle_args *dma_spec)
{
const char *s;
if (of_property_read_string_index(np, "dma-names", index, &s))
return -ENODEV;
if (strcmp(name, s))
return -ENODEV;
if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
dma_spec))
return -ENODEV;
return 0;
}
/**
* of_dma_request_slave_channel - Get the DMA slave channel
* @np: device node to get DMA request from
* @name: name of desired channel
*
* Returns pointer to appropriate DMA channel on success or an error pointer.
*/
struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
const char *name)
{
struct of_phandle_args dma_spec;
struct of_dma *ofdma;
struct dma_chan *chan;
int count, i, start;
int ret_no_channel = -ENODEV;
static atomic_t last_index;
if (!np || !name) {
pr_err("%s: not enough information provided\n", __func__);
return ERR_PTR(-ENODEV);
}
/* Silently fail if there is not even the "dmas" property */
if (!of_property_present(np, "dmas"))
return ERR_PTR(-ENODEV);
count = of_property_count_strings(np, "dma-names");
if (count < 0) {
pr_err("%s: dma-names property of node '%pOF' missing or empty\n",
__func__, np);
return ERR_PTR(-ENODEV);
}
/*
* approximate an average distribution across multiple
* entries with the same name
*/
start = atomic_inc_return(&last_index);
for (i = 0; i < count; i++) {
if (of_dma_match_channel(np, name,
(i + start) % count,
&dma_spec))
continue;
mutex_lock(&of_dma_lock);
ofdma = of_dma_find_controller(&dma_spec);
if (ofdma) {
chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
} else {
ret_no_channel = -EPROBE_DEFER;
chan = NULL;
}
mutex_unlock(&of_dma_lock);
of_node_put(dma_spec.np);
if (chan)
return chan;
}
return ERR_PTR(ret_no_channel);
}
EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);
/**
* of_dma_simple_xlate - Simple DMA engine translation function
* @dma_spec: pointer to DMA specifier as found in the device tree
* @ofdma: pointer to DMA controller data
*
* A simple translation function for devices that use a 32-bit value for the
* filter_param when calling the DMA engine dma_request_channel() function.
* Note that this translation function requires that #dma-cells is equal to 1
* and the argument of the dma specifier is the 32-bit filter_param. Returns
* pointer to appropriate dma channel on success or NULL on error.
*/
struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma)
{
int count = dma_spec->args_count;
struct of_dma_filter_info *info = ofdma->of_dma_data;
if (!info || !info->filter_fn)
return NULL;
if (count != 1)
return NULL;
return __dma_request_channel(&info->dma_cap, info->filter_fn,
&dma_spec->args[0], dma_spec->np);
}
EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
/**
* of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
* @dma_spec: pointer to DMA specifier as found in the device tree
* @ofdma: pointer to DMA controller data
*
* This function can be used as the of xlate callback for DMA driver which wants
* to match the channel based on the channel id. When using this xlate function
* the #dma-cells property of the DMA controller dt node needs to be set to 1.
* The data parameter of of_dma_controller_register must be a pointer to the
* dma_device struct the function should match upon.
*
* Returns pointer to appropriate dma channel on success or NULL on error.
*/
struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
struct of_dma *ofdma)
{
struct dma_device *dev = ofdma->of_dma_data;
struct dma_chan *chan, *candidate = NULL;
if (!dev || dma_spec->args_count != 1)
return NULL;
list_for_each_entry(chan, &dev->channels, device_node)
if (chan->chan_id == dma_spec->args[0]) {
candidate = chan;
break;
}
if (!candidate)
return NULL;
return dma_get_slave_channel(candidate);
}
EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);
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