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