drivers/acpi/acpi_platform.c. This limitation is only for the platform
devices, SPI and I2C devices are created automatically as described below.
+ DMA support
+ ~~~~~~~~~~~
+ DMA controllers enumerated via ACPI should be registered in the system to
+ provide generic access to their resources. For example, a driver that would
+ like to be accessible to slave devices via generic API call
+ dma_request_slave_channel() must register itself at the end of the probe
+ function like this:
+
+ err = devm_acpi_dma_controller_register(dev, xlate_func, dw);
+ /* Handle the error if it's not a case of !CONFIG_ACPI */
+
+ and implement custom xlate function if needed (usually acpi_dma_simple_xlate()
+ is enough) which converts the FixedDMA resource provided by struct
+ acpi_dma_spec into the corresponding DMA channel. A piece of code for that case
+ could look like:
+
+ #ifdef CONFIG_ACPI
+ struct filter_args {
+ /* Provide necessary information for the filter_func */
+ ...
+ };
+
+ static bool filter_func(struct dma_chan *chan, void *param)
+ {
+ /* Choose the proper channel */
+ ...
+ }
+
+ static struct dma_chan *xlate_func(struct acpi_dma_spec *dma_spec,
+ struct acpi_dma *adma)
+ {
+ dma_cap_mask_t cap;
+ struct filter_args args;
+
+ /* Prepare arguments for filter_func */
+ ...
+ return dma_request_channel(cap, filter_func, &args);
+ }
+ #else
+ static struct dma_chan *xlate_func(struct acpi_dma_spec *dma_spec,
+ struct acpi_dma *adma)
+ {
+ return NULL;
+ }
+ #endif
+
+ dma_request_slave_channel() will call xlate_func() for each registered DMA
+ controller. In the xlate function the proper channel must be chosen based on
+ information in struct acpi_dma_spec and the properties of the controller
+ provided by struct acpi_dma.
+
+ Clients must call dma_request_slave_channel() with the string parameter that
+ corresponds to a specific FixedDMA resource. By default "tx" means the first
+ entry of the FixedDMA resource array, "rx" means the second entry. The table
+ below shows a layout:
+
+ Device (I2C0)
+ {
+ ...
+ Method (_CRS, 0, NotSerialized)
+ {
+ Name (DBUF, ResourceTemplate ()
+ {
+ FixedDMA (0x0018, 0x0004, Width32bit, _Y48)
+ FixedDMA (0x0019, 0x0005, Width32bit, )
+ })
+ ...
+ }
+ }
+
+ So, the FixedDMA with request line 0x0018 is "tx" and next one is "rx" in
+ this example.
+
+ In robust cases the client unfortunately needs to call
+ acpi_dma_request_slave_chan_by_index() directly and therefore choose the
+ specific FixedDMA resource by its index.
+
SPI serial bus support
~~~~~~~~~~~~~~~~~~~~~~
Slave devices behind SPI bus have SpiSerialBus resource attached to them.
{
Name (SBUF, ResourceTemplate()
{
+ ...
+ // Used to power on/off the device
GpioIo (Exclusive, PullDefault, 0x0000, 0x0000,
IoRestrictionOutputOnly, "\\_SB.PCI0.GPI0",
0x00, ResourceConsumer,,)
// Pin List
0x0055
}
+
+ // Interrupt for the device
+ GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone,
+ 0x0000, "\\_SB.PCI0.GPI0", 0x00, ResourceConsumer,,)
+ {
+ // Pin list
+ 0x0058
+ }
+
...
- Return (SBUF)
}
+
+ Return (SBUF)
}
These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
acpi_get_gpio(path, gpio). This will return the Linux GPIO number or
negative errno if there was no translation found.
+In a simple case of just getting the Linux GPIO number from device
+resources one can use acpi_get_gpio_by_index() helper function. It takes
+pointer to the device and index of the GpioIo/GpioInt descriptor in the
+device resources list. For example:
+
+ int gpio_irq, gpio_power;
+ int ret;
+
+ gpio_irq = acpi_get_gpio_by_index(dev, 1, NULL);
+ if (gpio_irq < 0)
+ /* handle error */
+
+ gpio_power = acpi_get_gpio_by_index(dev, 0, NULL);
+ if (gpio_power < 0)
+ /* handle error */
+
+ /* Now we can use the GPIO numbers */
+
Other GpioIo parameters must be converted first by the driver to be
suitable to the gpiolib before passing them.
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_device.h>
+ #include <linux/of_dma.h>
#include "at_hdmac_regs.h"
#include "dmaengine.h"
dev_vdbg(chan2dev(&atchan->chan_common), "complete all\n");
- BUG_ON(atc_chan_is_enabled(atchan));
-
/*
* Submit queued descriptors ASAP, i.e. before we go through
* the completed ones.
{
dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n");
+ if (atc_chan_is_enabled(atchan))
+ return;
+
if (list_empty(&atchan->active_list) ||
list_is_singular(&atchan->active_list)) {
atc_complete_all(atchan);
ctrlb |= ATC_DST_ADDR_MODE_FIXED
| ATC_SRC_ADDR_MODE_INCR
| ATC_FC_MEM2PER
- | ATC_SIF(AT_DMA_MEM_IF) | ATC_DIF(AT_DMA_PER_IF);
+ | ATC_SIF(atchan->mem_if) | ATC_DIF(atchan->per_if);
reg = sconfig->dst_addr;
for_each_sg(sgl, sg, sg_len, i) {
struct at_desc *desc;
ctrlb |= ATC_DST_ADDR_MODE_INCR
| ATC_SRC_ADDR_MODE_FIXED
| ATC_FC_PER2MEM
- | ATC_SIF(AT_DMA_PER_IF) | ATC_DIF(AT_DMA_MEM_IF);
+ | ATC_SIF(atchan->per_if) | ATC_DIF(atchan->mem_if);
reg = sconfig->src_addr;
for_each_sg(sgl, sg, sg_len, i) {
desc->lli.ctrlb = ATC_DST_ADDR_MODE_FIXED
| ATC_SRC_ADDR_MODE_INCR
| ATC_FC_MEM2PER
- | ATC_SIF(AT_DMA_MEM_IF)
- | ATC_DIF(AT_DMA_PER_IF);
+ | ATC_SIF(atchan->mem_if)
+ | ATC_DIF(atchan->per_if);
break;
case DMA_DEV_TO_MEM:
desc->lli.ctrlb = ATC_DST_ADDR_MODE_INCR
| ATC_SRC_ADDR_MODE_FIXED
| ATC_FC_PER2MEM
- | ATC_SIF(AT_DMA_PER_IF)
- | ATC_DIF(AT_DMA_MEM_IF);
+ | ATC_SIF(atchan->per_if)
+ | ATC_DIF(atchan->mem_if);
break;
default:
return;
spin_lock_irqsave(&atchan->lock, flags);
- if (!atc_chan_is_enabled(atchan)) {
- atc_advance_work(atchan);
- }
+ atc_advance_work(atchan);
spin_unlock_irqrestore(&atchan->lock, flags);
}
dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
}
+ #ifdef CONFIG_OF
+ static bool at_dma_filter(struct dma_chan *chan, void *slave)
+ {
+ struct at_dma_slave *atslave = slave;
+
+ if (atslave->dma_dev == chan->device->dev) {
+ chan->private = atslave;
+ return true;
+ } else {
+ return false;
+ }
+ }
+
+ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
+ struct of_dma *of_dma)
+ {
+ struct dma_chan *chan;
+ struct at_dma_chan *atchan;
+ struct at_dma_slave *atslave;
+ dma_cap_mask_t mask;
+ unsigned int per_id;
+ struct platform_device *dmac_pdev;
+
+ if (dma_spec->args_count != 2)
+ return NULL;
+
+ dmac_pdev = of_find_device_by_node(dma_spec->np);
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+
+ atslave = devm_kzalloc(&dmac_pdev->dev, sizeof(*atslave), GFP_KERNEL);
+ if (!atslave)
+ return NULL;
+ /*
+ * We can fill both SRC_PER and DST_PER, one of these fields will be
+ * ignored depending on DMA transfer direction.
+ */
+ per_id = dma_spec->args[1];
+ atslave->cfg = ATC_FIFOCFG_HALFFIFO | ATC_DST_H2SEL_HW
+ | ATC_SRC_H2SEL_HW | ATC_DST_PER(per_id)
+ | ATC_SRC_PER(per_id);
+ atslave->dma_dev = &dmac_pdev->dev;
+
+ chan = dma_request_channel(mask, at_dma_filter, atslave);
+ if (!chan)
+ return NULL;
+
+ atchan = to_at_dma_chan(chan);
+ atchan->per_if = dma_spec->args[0] & 0xff;
+ atchan->mem_if = (dma_spec->args[0] >> 16) & 0xff;
+
+ return chan;
+ }
+ #else
+ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
+ struct of_dma *of_dma)
+ {
+ return NULL;
+ }
+ #endif
/*-- Module Management -----------------------------------------------*/
for (i = 0; i < plat_dat->nr_channels; i++) {
struct at_dma_chan *atchan = &atdma->chan[i];
+ atchan->mem_if = AT_DMA_MEM_IF;
+ atchan->per_if = AT_DMA_PER_IF;
atchan->chan_common.device = &atdma->dma_common;
dma_cookie_init(&atchan->chan_common);
list_add_tail(&atchan->chan_common.device_node,
dma_async_device_register(&atdma->dma_common);
+ /*
+ * Do not return an error if the dmac node is not present in order to
+ * not break the existing way of requesting channel with
+ * dma_request_channel().
+ */
+ if (pdev->dev.of_node) {
+ err = of_dma_controller_register(pdev->dev.of_node,
+ at_dma_xlate, atdma);
+ if (err) {
+ dev_err(&pdev->dev, "could not register of_dma_controller\n");
+ goto err_of_dma_controller_register;
+ }
+ }
+
return 0;
+ err_of_dma_controller_register:
+ dma_async_device_unregister(&atdma->dma_common);
+ dma_pool_destroy(atdma->dma_desc_pool);
err_pool_create:
platform_set_drvdata(pdev, NULL);
free_irq(platform_get_irq(pdev, 0), atdma);
return err;
}
- static int __exit at_dma_remove(struct platform_device *pdev)
+ static int at_dma_remove(struct platform_device *pdev)
{
struct at_dma *atdma = platform_get_drvdata(pdev);
struct dma_chan *chan, *_chan;
};
static struct platform_driver at_dma_driver = {
- .remove = __exit_p(at_dma_remove),
+ .remove = at_dma_remove,
.shutdown = at_dma_shutdown,
.id_table = atdma_devtypes,
.driver = {
projects / karo-tx-linux.git / commitdiff