diff options
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/Kconfig | 4 | ||||
| -rw-r--r-- | drivers/dma/Makefile | 2 | ||||
| -rw-r--r-- | drivers/dma/of-dma.c | 264 |
3 files changed, 270 insertions, 0 deletions
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index 0b408bbb6a1..e92b5f0f8a5 100644 --- a/drivers/dma/Kconfig +++ b/drivers/dma/Kconfig @@ -325,6 +325,10 @@ config DMA_ENGINE config DMA_VIRTUAL_CHANNELS tristate +config DMA_OF + def_bool y + depends on OF + comment "DMA Clients" depends on DMA_ENGINE diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile index 7428feaa870..c1ed644be9e 100644 --- a/drivers/dma/Makefile +++ b/drivers/dma/Makefile @@ -3,6 +3,8 @@ ccflags-$(CONFIG_DMADEVICES_VDEBUG) += -DVERBOSE_DEBUG obj-$(CONFIG_DMA_ENGINE) += dmaengine.o obj-$(CONFIG_DMA_VIRTUAL_CHANNELS) += virt-dma.o +obj-$(CONFIG_DMA_OF) += of-dma.o + obj-$(CONFIG_NET_DMA) += iovlock.o obj-$(CONFIG_INTEL_MID_DMAC) += intel_mid_dma.o obj-$(CONFIG_DMATEST) += dmatest.o diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c new file mode 100644 index 00000000000..59631b2c466 --- /dev/null +++ b/drivers/dma/of-dma.c @@ -0,0 +1,264 @@ +/* + * 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); + + if (list_empty(&of_dma_list)) { + spin_unlock(&of_dma_lock); + return NULL; + } + + 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; + + 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; + + nbcells = be32_to_cpup(of_get_property(np, "#dma-cells", NULL)); + if (!nbcells) { + pr_err("%s: #dma-cells property is missing or invalid\n", + __func__); + 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 */ + list_add_tail(&ofdma->of_dma_controllers, &of_dma_list); + + 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, 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, + 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); |