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Message-ID: <4742258.TBitC3hVuO@wuerfel>
Date: Tue, 04 Nov 2014 17:25:58 +0100
From: Arnd Bergmann <arnd@...db.de>
To: Grant Likely <grant.likely@...aro.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Rob Herring <robherring2@...il.com>,
Gilad Avidov <gavidov@...eaurora.org>,
Rob Herring <robh+dt@...nel.org>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Sagar Dharia <sdharia@...eaurora.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
David Woodhouse <dwmw2@...radead.org>,
Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCH 0/1] Compact interface for Device-Tree
On Tuesday 04 November 2014 15:53:29 Grant Likely wrote:
> On Mon, 03 Nov 2014 16:06:03 +0100
> , Arnd Bergmann <arnd@...db.de>
> wrote:
> > On Friday 31 October 2014 23:53:28 Rafael J. Wysocki wrote:
> > > On Saturday, November 01, 2014 05:13:45 AM Rob Herring wrote:
> > > > On Fri, Oct 31, 2014 at 6:59 AM, Gilad Avidov <gavidov@...eaurora.org> wrote:
> > > > >
> > > > > Device-Tree compact API
> > > > > ------------------------
> > > > >
> > > > > Common code seen in driverâs probe reads device tree values and handling
> > > > > erroneous return codes from all those of_property_read_xxx() APIs. This
> > > > > common code is factored out by the of_property_map module which allows
> > > > > driverâs probe to replace that (often lengthy) code with a concise table:
> > > > >
> > > > > struct of_prop_map map[] = {
> > > > > {"i2c", &dev->id, OF_REQ, OF_ID, -1},
> > > > > {"qcom,clk-freq-out", &dev->clk_freq_out, OF_REQ, OF_U32, 0},
> > > > > {"qcom,clk-freq-in", &dev->clk_freq_in, OF_REQ, OF_U32, 0},
> > > > > {"qcom,disable-dma", &dev->disable_dma, OF_OPT, OF_BOOL, 0},
> > > > > {"qcom,master-id", &dev->mstr_id, OF_SGST, OF_U32, 0},
> > > > > {NULL, NULL, 0, 0, 0},
> > > > > };
> > > > >
> > > > > Then call populate to read the values into the deviceâs variables:
> > > > >
> > > > > ret = of_prop_populate(dev, dev->of_node, map);
> > > >
> > > > Interesting idea. The main concern I have with this is there has been
> > > > on-going discussions about how to generalize property handling across
> > > > DT and ACPI to make drivers more agnostic, so I'm copying a few folks
> > > > involved in that. That may be a bit orthogonal to what this is doing,
> > > > but we may want some coordination here.
> > >
> > > Agreed.
> > >
> > > We actually have a patchset adding a unified device property API in
> > > linux-next (http://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/log/?h=device-properties)
> > > and I'd prefer to see the "compactization" to happen at that level, if possible,
> > > rather that for of_ only.
> >
> > Agreed, this should definitely use the new generalized API.
> > I have prototyped a similar concept last year, which actually went much
> > further and also abstracted high-level properties such as interrupts,
> > gpios, pwm, dma-engine, etc. I still think we should do something
> > like that, but I've never had the time to follow up and nobody else
> > picked up my work from back then.
> >
> > Would others like to see that?
>
> Absolutely. I also tried to do the same thing and didn't get very far.
> And, yes, it should be done at the level of the device properties API.
This is taken from an old email I sent last year on the subject "Re:
[RFC PATCH dtc] C-based DT schema checker integrated into dtc". I haven't
actually followed up at all, and couldn't find the file now, so this
is all I have.
Arnd
#if 0
/* allocate drvdata */
DEVM_ALLOC,
/* request hardware properties */
DEVM_IRQ,
DEVM_IOMAP,
DEVM_GPIO,
DEVM_DMA_SLAVE,
DEVM_PINCTRL,
DEVM_REGULATOR,
DEVM_CLK,
DEVM_PWM,
DEVM_USBPHY,
/* auxiliary information */
DEVM_PROP_BOOL
DEVM_PROP_U32
DEVM_PROP_STRING
#endif
#error don't bother compiling this file, it's only proof-of-concept
struct device;
struct devm_probe {
int (*initfunc)(struct device *dev, const struct devm_probe *probe);
ptrdiff_t offset;
unsigned int index;
const char *name;
void *arg;
unsigned int flags;
};
/* like offsetof(), but ensures that MEMBER is of type MEMBERTYPE */
#define offsetof_t(TYPE, MEMBER, MEMBERTYPE) \
((typeof(MEMBER)*)0 - typeof(MEMBERTYPE*)0 + offsetof((TYPE), (MEMBER)))
/* cast 'ptr' to void* and cause a build warning if it wasn't of 'type' before */
#define typecheck_ptr(ptr, type) \
(void *)(ptr - (type)NULL + (type)NULL)
/*
* This is the main entry point for drivers:
*
* Given an zero-terminated array of 'struct devm_probe' entries,
* this calls all initfunc pointers in the given order. Each initfunc
* may manipulate a field in the driver_data, as pointed to by
* the 'offset' member.
*/
int devm_probe(struct device *dev, const struct devm_probe *probe)
{
int ret;
for (ret = 0; !ret && probe->initfunc, probe++)
ret = probe->initfunc(dev, probe);
return ret;
}
EXPORT_SYMBOL_GPL(devm_probe);
/*
* this must be the called before any of the others, or not at
* all, if dev_set_drvdata() has already been called.
*/
static void devm_probe_alloc_release(struct device *dev, void *res)
{
dev_set_drvdata(dev, NULL);
}
int devm_probe_alloc(struct device *dev, const struct devm_probe *probe)
{
void *dr;
if (dev_get_drvdata)
return -EBUSY;
dr = alloc_dr(devm_probe_alloc_release, probe->offset, GFP_KERNEL);
if (unlikely(!dr))
return -ENOMEM;
dev_set_drvdata(dev, dr);
set_node_dbginfo(&dr->node, "devm_probe_alloc", size);
devres_add(dev, dr->data);
}
EXPORT_SYMBOL_GPL(devm_probe_alloc);
#define DEVM_ALLOC(_struct) \
{ .initfunc = devm_probe_alloc, .offset = sizeof(struct _struct), }
int devm_probe_irq(struct device *dev, const struct devm_probe *probe)
{
int ret;
int irq;
int *irqp;
int index;
const char *name;
/* come up with a reasonable string for the irq name,
maybe create devm_kasprintf() to allow arbitrary length? */
name = devm_kmalloc(dev, 32, GFP_KERNEL);
if (!name)
return -ENOMEM;
if (probe->name)
snprintf(name, 32 - 1, "%s:%s", dev_name(dev), probe->name);
else
snprintf(name, 32 - 1, "%s:%n", dev_name(dev), probe->index);
/* find IRQ number from resource if platform device */
irq = 0;
if (dev->bus_type == &platform_bus) {
struct platform_device *pdev = to_platform_device(dev);
if (probe->name)
irq = platform_get_irq_byname(pdev, probe->name);
else
irq = platform_get_irq(pdev, probe->index);
}
/* try getting irq number from device tree if that failed */
if (!irq && dev->of_node) {
if (probe->name)
index = of_property_match_string(dev->of_node,
"interrupt-names",
probe->name);
else
index = probe->index;
irq = irq_of_parse_and_map(dev->of_node, index);
}
/* copy irq number to driver data */
irqp = dev_get_drvdata(dev) + probe->offset;
*irqp = irq;
return devm_request_irq(dev, irq, probe->arg, probe->flags, name, probe->dev);
}
EXPORT_SYMBOL_GPL(devm_probe_irq);
#define DEVM_IRQ(_struct, _member, _index, _handler, _flags) { \
.initfunc = devm_probe_irq, \
.offset = offsetof_t(struct _struct, _member, int), \
.index = _index, \
.arg = typecheck_ptr((_handler), irq_handler_t), \
.flags = _flags, \
}
#define DEVM_IRQ_NAMED(_struct, _member, _name, _handler, _flags) { \
.initfunc = devm_probe_irq, \
.offset = offsetof_t(struct _struct, _member, int), \
.name = _name, \
.arg = typecheck_ptr((_handler), irq_handler_t), \
.flags = _flags, \
}
#define DEVM_IOMAP_NOREQUEST 1
int devm_probe_iomap(struct device *dev, const struct devm_probe *probe)
{
struct resource res, *resp;
void __iomem *vaddr;
void * __iomem *vaddrp;
int ret;
/* find mem resource from platform device */
if (dev->bus_type == &platform_bus) {
struct platform_device *pdev = to_platform_device(dev);
if (probe->name)
resp = platform_get_resource_byname(pdev,
IORESOURCE_MEM, probe->name);
else
resp = platform_get_resource(pdev,
IORESOURCE_MEM, probe->index);
}
/* try getting resource from device tree if that failed */
if (!resp && dev->of_node) {
if (probe->name)
index = of_property_match_string(dev->of_node,
"reg-names",
probe->name);
else
index = probe->index;
ret = of_address_to_resource(dev->of_node, index, &res);
if (ret)
return ret;
resp = &res;
}
if (probe->flags & DEVM_IOMAP_NOREQUEST) {
vaddr = devm_ioremap(dev, resp->start, resource_size(resp));
if (!vaddr)
return -EINVAL;
} else {
vaddr = devm_ioremap_resource(dev, resp);
if (IS_ERR(vaddr))
return PTR_ERR(vaddr);
}
vaddrp = dev_get_drvdata(dev) + probe->offset;
*vaddrp = vaddr;
return 0;
}
EXPORT_SYMBOL_GPL(devm_probe_iomap);
#define DEVM_IOMAP(_struct, _member, _index, _flags) { \
.initfunc = devm_probe_iomap, \
.offset = offsetof_t(struct _struct, _member, void __iomem *), \
.index = _index, \
.flags = _flags, \
}
#define DEVM_IOMAP_NAMED(_struct, _member, _name, _flags) { \
.initfunc = devm_probe_iomap, \
.offset = offsetof_t(struct _struct, _member, void __iomem *), \
.name = _name, \
.flags = _flags, \
}
int devm_probe_gpio(struct device *dev, const struct devm_probe *probe)
{
struct gpio_desc *desc, **descp;
desc = devm_gpiod_get_index(dev, probe->name, probe->index);
if (IS_ERR(desc)) {
/* FIXME: this looks wrong */
desc = of_get_named_gpiod_flags(dev->of_node, probe->name,
probe->index, NULL);
if (IS_ERR(desc))
return PTR_ERR(desc);
devm_gpio_request(dev, desc_to_gpio(desc), probe->name);
}
descp = dev_get_drvdata(dev) + probe->offset;
*descp = desc;
return 0;
}
#define DEVM_GPIO(_struct, _member, _index) { \
.initfunc = devm_probe_iomap, \
.offset = offsetof_t(struct _struct, _member, struct gpio_desc*),\
.name = "gpios", \
.index = _index, \
}
#define DEVM_GPIO_NAMED(_struct, _member, _name) { \
.initfunc = devm_probe_iomap, \
.offset = offsetof_t(struct _struct, _member, struct gpio_desc*),\
.name = _name, \
}
static void devm_probe_dma_release(struct device *dev, void *chanp)
{
dma_release_channel(*(struct dma_chan**)chanp);
}
int devm_probe_dma(struct device *dev, const struct devm_probe *probe)
{
struct dma_chan *chan, **chanp;
/* there is no devm_dma_request_channel yet, so build our own */
chanp = devres_alloc(devm_probe_dma_release, sizeof(chanp), GFP_KERNEL);
if (!chanp)
return -ENOMEM;
chan = dma_request_slave_channel(dev, probe->name);
if (!chan) {
devres_free(chanp);
return -EINVAL;
}
*chanp = chan;
devres_add(dev, chanp);
/* add pointer to the private data */
chanp = dev_get_drvdata(dev) + probe->offset;
*chanp = chan;
return 0;
}
#define DEVM_DMA_SLAVE(_struct, _member, _name) \
.offset = offsetof_t(struct _struct, _member, struct dma_chan*),\
.name = _name, \
}
/*
* simple properties: bool, u32, string
* no actual need for managed interfaces, just a way to abstract the
* access to DT or other information source
*/
int devm_probe_prop_bool(struct device *dev, struct devm_probe *probe)
{
bool *val;
val = dev_get_drvdata(dev) + probe->offset;
*val = of_property_read_bool(dev->of_node, probe->name);
return 0;
}
EXPORT_SYMBOL_GPL(devm_probe_prop_bool);
#define DEVM_PROP_BOOL(_struct, _member, _name) \
.offset = offsetof_t(struct _struct, _member, bool), \
.name = _name, \
}
int devm_probe_prop_u32(struct device *dev, struct devm_probe *probe)
{
u32 *val;
int ret;
val = dev_get_drvdata(dev) + probe->offset;
ret = of_property_read_u32(dev->of_node, probe->name, val);
return ret;
}
EXPORT_SYMBOL_GPL(devm_probe_prop_bool);
#define DEVM_PROP_U32(_struct, _member, _name) \
.offset = offsetof_t(struct _struct, _member, u32), \
.name = _name, \
}
int devm_probe_prop_string(struct device *dev, struct devm_probe *probe)
{
const char **val;
int ret;
val = dev_get_drvdata(dev) + probe->offset;
ret = of_property_read_string(dev->of_node, probe->name, val);
return ret;
}
EXPORT_SYMBOL_GPL(devm_probe_prop_bool);
#define DEVM_PROP_STRING(_struct, _member, _name) \
.offset = offsetof_t(struct _struct, _member, const char *), \
.name = _name, \
}
/* example driver */
struct foo_priv {
spinlock_t lock;
void __iomem *regs;
int irq;
struct gpio_desc *gpio;
struct dma_chan *rxdma;
struct dma_chan *txdma;
bool oldstyle_dma;
};
static irqreturn_t foo_irq_handler(int irq, void *dev);
/*
* this lists all properties we access from the driver. The list
* is interpreted by devm_probe() and can be programmatically
* verified to match the binding.
*/
static const struct devm_probe foo_probe_list[] = {
DEVM_ALLOC(foo_priv),
DEVM_IOMAP(foo_priv, regs, 0, 0),
DEVM_PROP_BOOL(foo_priv, oldstyle_dma, "foo,oldstyle-dma"),
DEVM_DMA_SLAVE(foo_priv, rxdma, "rx");
DEVM_DMA_SLAVE(foo_priv, txdma, "tx");
DEVM_GPIO(foo_priv, gpio, 0);
DEVM_IRQ_NAMED(foo_priv, irq, foo_irq_handler, "fifo", IRQF_SHARED),
{},
};
static int foo_probe(struct platform_device *dev)
{
int ret;
ret = devm_probe(dev->dev, foo_probe_list);
if (ret)
return ret;
return bar_subsystem_register(&foo_bar_ops, dev);
}
--
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