diff options
Diffstat (limited to '')
-rw-r--r-- | drivers/dma/of-dma.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c new file mode 100644 index 000000000..4be433482 --- /dev/null +++ b/drivers/dma/of-dma.c @@ -0,0 +1,361 @@ +// 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 retuned. A NULL pointer is returned if no match is + * found. + */ +static struct of_dma *of_dma_find_controller(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 { + chan->router = ofdma->dma_router; + chan->route_data = route_data; + } + +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_find_property(np, "dmas", NULL)) + 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 propety 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); |