| /* |
| * Device tree helpers for DMA request / controller |
| * |
| * Based on of_gpio.c |
| * |
| * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/ |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include <linux/device.h> |
| #include <linux/err.h> |
| #include <linux/module.h> |
| #include <linux/rculist.h> |
| #include <linux/slab.h> |
| #include <linux/of.h> |
| #include <linux/of_dma.h> |
| |
| static LIST_HEAD(of_dma_list); |
| static DEFINE_SPINLOCK(of_dma_lock); |
| |
| /** |
| * of_dma_get_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 the use_count |
| * variable is increased and 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_get_controller(struct of_phandle_args *dma_spec) |
| { |
| struct of_dma *ofdma; |
| |
| spin_lock(&of_dma_lock); |
| |
| list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
| if ((ofdma->of_node == dma_spec->np) && |
| (ofdma->of_dma_nbcells == dma_spec->args_count)) { |
| ofdma->use_count++; |
| spin_unlock(&of_dma_lock); |
| return ofdma; |
| } |
| |
| spin_unlock(&of_dma_lock); |
| |
| pr_debug("%s: can't find DMA controller %s\n", __func__, |
| dma_spec->np->full_name); |
| |
| return NULL; |
| } |
| |
| /** |
| * of_dma_put_controller - Decrement use count for a registered DMA controller |
| * @of_dma: pointer to DMA controller data |
| * |
| * Decrements the use_count variable in the DMA data structure. This function |
| * should be called only when a valid pointer is returned from |
| * of_dma_get_controller() and no further accesses to data referenced by that |
| * pointer are needed. |
| */ |
| static void of_dma_put_controller(struct of_dma *ofdma) |
| { |
| spin_lock(&of_dma_lock); |
| ofdma->use_count--; |
| spin_unlock(&of_dma_lock); |
| } |
| |
| /** |
| * 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; |
| int nbcells; |
| const __be32 *prop; |
| |
| 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; |
| |
| prop = of_get_property(np, "#dma-cells", NULL); |
| if (prop) |
| nbcells = be32_to_cpup(prop); |
| |
| if (!prop || !nbcells) { |
| pr_err("%s: #dma-cells property is missing or invalid\n", |
| __func__); |
| kfree(ofdma); |
| return -EINVAL; |
| } |
| |
| ofdma->of_node = np; |
| ofdma->of_dma_nbcells = nbcells; |
| ofdma->of_dma_xlate = of_dma_xlate; |
| ofdma->of_dma_data = data; |
| ofdma->use_count = 0; |
| |
| /* Now queue of_dma controller structure in list */ |
| spin_lock(&of_dma_lock); |
| list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); |
| spin_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. |
| */ |
| int of_dma_controller_free(struct device_node *np) |
| { |
| struct of_dma *ofdma; |
| |
| spin_lock(&of_dma_lock); |
| |
| if (list_empty(&of_dma_list)) { |
| spin_unlock(&of_dma_lock); |
| return -ENODEV; |
| } |
| |
| list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) |
| if (ofdma->of_node == np) { |
| if (ofdma->use_count) { |
| spin_unlock(&of_dma_lock); |
| return -EBUSY; |
| } |
| |
| list_del(&ofdma->of_dma_controllers); |
| spin_unlock(&of_dma_lock); |
| kfree(ofdma); |
| return 0; |
| } |
| |
| spin_unlock(&of_dma_lock); |
| return -ENODEV; |
| } |
| EXPORT_SYMBOL_GPL(of_dma_controller_free); |
| |
| /** |
| * 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 NULL on error. |
| */ |
| 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; |
| |
| if (!np || !name) { |
| pr_err("%s: not enough information provided\n", __func__); |
| return NULL; |
| } |
| |
| count = of_property_count_strings(np, "dma-names"); |
| if (count < 0) { |
| pr_err("%s: dma-names property missing or empty\n", __func__); |
| return NULL; |
| } |
| |
| for (i = 0; i < count; i++) { |
| if (of_dma_match_channel(np, name, i, &dma_spec)) |
| continue; |
| |
| ofdma = of_dma_get_controller(&dma_spec); |
| |
| if (!ofdma) |
| continue; |
| |
| chan = ofdma->of_dma_xlate(&dma_spec, ofdma); |
| |
| of_dma_put_controller(ofdma); |
| |
| of_node_put(dma_spec.np); |
| |
| if (chan) |
| return chan; |
| } |
| |
| return NULL; |
| } |
| |
| /** |
| * of_dma_simple_xlate - Simple DMA engine translation function |
| * @dma_spec: pointer to DMA specifier as found in the device tree |
| * @of_dma: 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]); |
| } |
| EXPORT_SYMBOL_GPL(of_dma_simple_xlate); |