358 lines
10 KiB
C
358 lines
10 KiB
C
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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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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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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* @of_dma: 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 (chan) {
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chan->router = ofdma->dma_router;
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chan->route_data = route_data;
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} else {
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ofdma->dma_router->route_free(ofdma->dma_router->dev,
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route_data);
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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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* @of_dma: 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]);
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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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* @of_dma: 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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