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SubjectRe: [PATCH 1/3] serial/imx: add device tree support
On Tue, Jun 21, 2011 at 01:13:50PM -0600, Grant Likely wrote:
[...]
> >
> >  /**
> > + *     of_get_device_index - Get device index by looking up "aliases" node
> > + *     @np:    Pointer to device node that asks for device index
> > + *     @name:  The device alias without index number
> > + *
> > + *     Returns the device index if find it, else returns -ENODEV.
> > + */
> > +int of_get_device_index(struct device_node *np, const char *alias)
> > +{
> > +       struct device_node *aliases = of_find_node_by_name(NULL, "aliases");
> > +       struct property *prop;
> > +       char name[32];
> > +       int index = 0;
> > +
> > +       if (!aliases)
> > +               return -ENODEV;
> > +
> > +       while (1) {
> > +               snprintf(name, sizeof(name), "%s%d", alias, index);
> > +               prop = of_find_property(aliases, name, NULL);
> > +               if (!prop)
> > +                       return -ENODEV;
> > +               if (np == of_find_node_by_path(prop->value))
> > +                       break;
> > +               index++;
> > +       }
>
> Rather than parsing the alias strings everytime, it would probably be
> better to preprocess all the properties in the aliases node and create
> a lookup table of alias->node references that can be walked quickly
> and trivially.
>
> Also, when obtaining an enumeration for a device, you'll need to be
> careful about what number gets returned. If the node doesn't match a
> given alias, but aliases do exist for other devices of like type, then
> you need to be careful not to assign a number already assigned to
> another device via an alias (this of course assumes the driver
> supports dynamics enumeration, which many drivers will). It would be
>

Grant, please take a look at the second shot below. Please let me
know what you think.

diff --git a/arch/arm/boot/dts/imx51-babbage.dts b/arch/arm/boot/dts/imx51-babbage.dts
index 7976932..f4a5c3c 100644
--- a/arch/arm/boot/dts/imx51-babbage.dts
+++ b/arch/arm/boot/dts/imx51-babbage.dts
@@ -18,6 +18,12 @@
compatible = "fsl,imx51-babbage", "fsl,imx51";
interrupt-parent = <&tzic>;

+ aliases {
+ serial0 = &uart0;
+ serial1 = &uart1;
+ serial2 = &uart2;
+ };
+
chosen {
bootargs = "console=ttymxc0,115200 root=/dev/mmcblk0p3 rootwait";
};
@@ -47,29 +53,29 @@
reg = <0x70000000 0x40000>;
ranges;

- uart@7000c000 {
- compatible = "fsl,imx51-uart", "fsl,imx-uart";
+ uart2: uart@7000c000 {
+ compatible = "fsl,imx51-uart", "fsl,imx21-uart";
reg = <0x7000c000 0x4000>;
interrupts = <33>;
id = <3>;
fsl,has-rts-cts;
};
};

- uart@73fbc000 {
- compatible = "fsl,imx51-uart", "fsl,imx-uart";
+ uart0: uart@73fbc000 {
+ compatible = "fsl,imx51-uart", "fsl,imx21-uart";
reg = <0x73fbc000 0x4000>;
interrupts = <31>;
id = <1>;
fsl,has-rts-cts;
};

- uart@73fc0000 {
- compatible = "fsl,imx51-uart", "fsl,imx-uart";
+ uart1: uart@73fc0000 {
+ compatible = "fsl,imx51-uart", "fsl,imx21-uart";
reg = <0x73fc0000 0x4000>;
interrupts = <32>;
id = <2>;
fsl,has-rts-cts;
};
};

diff --git a/arch/arm/mach-mx5/imx51-dt.c b/arch/arm/mach-mx5/imx51-dt.c
index 8bfdb91..e6c7298 100644
--- a/arch/arm/mach-mx5/imx51-dt.c
+++ b/arch/arm/mach-mx5/imx51-dt.c
@@ -40,6 +40,8 @@ static const struct of_device_id tzic_of_match[] __initconst = {

static void __init imx51_dt_init(void)
{
+ of_scan_aliases();
+
irq_domain_generate_simple(tzic_of_match, MX51_TZIC_BASE_ADDR, 0);

of_platform_populate(NULL, of_default_bus_match_table,
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 632ebae..90349a2 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -17,12 +17,27 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>

+struct alias_devname {
+ char devname[32];
+ struct list_head link;
+ struct list_head head;
+};
+
+struct alias_devid {
+ int devid;
+ struct device_node *node;
+ struct list_head link;
+};
+
+static LIST_HEAD(aliases_lookup);
+
struct device_node *allnodes;
struct device_node *of_chosen;

@@ -922,3 +937,170 @@ out_unlock:
}
#endif /* defined(CONFIG_OF_DYNAMIC) */

+/*
+ * get_alias_dev_name_id - Get device name and id from alias name
+ *
+ * an: The alias name passed in
+ * dn: The pointer used to return device name
+ *
+ * Returns device id which should be the number at the end of alias
+ * name, otherwise returns -1.
+ */
+static int get_alias_name_id(char *an, char *dn)
+{
+ int len = strlen(an);
+ char *end = an + len;
+
+ while (isdigit(*--end))
+ len--;
+
+ end++;
+ strncpy(dn, an, len);
+ dn[len] = '\0';
+
+ return strlen(end) ? simple_strtol(end, NULL, 10) : -1;
+}
+
+/*
+ * get_an_available_devid - Get an available devid for the given devname
+ *
+ * adn: The pointer to the given alias_devname
+ *
+ * Returns the available devid
+ */
+static int get_an_available_devid(struct alias_devname *adn)
+{
+ int devid = 0;
+ struct alias_devid *adi;
+
+ while (1) {
+ bool used = false;
+ list_for_each_entry(adi, &adn->head, link) {
+ if (adi->devid == devid) {
+ used = true;
+ break;
+ }
+ }
+
+ if (!used)
+ break;
+
+ devid++;
+ }
+
+ return devid;
+}
+
+/*
+ * of_scan_aliases - Scan all properties of aliases node and populate the
+ * global lookup table with the device name and id info
+ *
+ * Returns the number of aliases properties found, or error code in error case.
+ */
+int of_scan_aliases(void)
+{
+ struct device_node *aliases = of_find_node_by_name(NULL, "aliases");
+ struct property *pp;
+ struct alias_devname *adn;
+ struct alias_devid *adi;
+ int ret = 0;
+
+ if (!aliases) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ for (pp = aliases->properties; pp != NULL; pp = pp->next) {
+ bool found = false;
+ char devname[32];
+ int devid = get_alias_name_id(pp->name, devname);
+
+ /* We do not want to proceed this sentinel one */
+ if (!strcmp(pp->name, "name") && !strcmp(pp->value, "aliases"))
+ break;
+
+ /* See if the devname already exists */
+ list_for_each_entry(adn, &aliases_lookup, link) {
+ if (!strcmp(adn->devname, devname)) {
+ found = true;
+ break;
+ }
+ }
+
+ /*
+ * Create the entry for this devname if not found,
+ * and add it into aliases_lookup
+ */
+ if (!found) {
+ adn = kzalloc(sizeof(*adn), GFP_KERNEL);
+ if (!adn) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ strcpy(adn->devname, devname);
+ INIT_LIST_HEAD(&adn->head);
+ list_add_tail(&adn->link, &aliases_lookup);
+ }
+
+ /*
+ * Save the devid as one entry of the list for this
+ * specified devname
+ */
+ adi = kzalloc(sizeof(*adi), GFP_KERNEL);
+ if (!adi) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ adi->devid = (devid == -1) ? get_an_available_devid(adn) :
+ devid;
+ adi->node = of_find_node_by_path(pp->value);
+
+ list_add_tail(&adi->link, &adn->head);
+ ret++;
+ }
+
+out:
+ return ret;
+}
+
+/**
+ * of_get_device_id - Get device id by looking up "aliases" node
+ * @np: Pointer to device node that asks for device id
+ * @name: The device alias name
+ *
+ * Returns the device id if find it, else returns -ENODEV.
+ */
+int of_get_device_id(struct device_node *np, const char *name)
+{
+ struct alias_devname *adn;
+ struct alias_devid *adi;
+ bool found = false;
+ int ret;
+
+ list_for_each_entry(adn, &aliases_lookup, link) {
+ if (!strcmp(adn->devname, name)) {
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ found = false;
+ list_for_each_entry(adi, &adn->head, link) {
+ if (np == adi->node) {
+ found = true;
+ break;
+ }
+ }
+
+ ret = found ? adi->devid : -ENODEV;
+out:
+ return ret;
+}
+EXPORT_SYMBOL(of_get_device_id);
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 2769353..062639e 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1225,43 +1265,33 @@ static int serial_imx_resume(struct platform_device *dev)
return 0;
}

static int serial_imx_probe_dt(struct imx_port *sport,
struct platform_device *pdev)
{
struct device_node *node = pdev->dev.of_node;
- const __be32 *line;
+ int line;

if (!node)
return -ENODEV;

- line = of_get_property(node, "id", NULL);
- if (!line)
+ line = of_get_device_id(node, "serial");
+ if (IS_ERR_VALUE(line))
return -ENODEV;

- sport->port.line = be32_to_cpup(line) - 1;
+ sport->port.line = line;

diff --git a/include/linux/of.h b/include/linux/of.h
index bfc0ed1..270c671 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -213,6 +213,9 @@ extern int of_parse_phandles_with_args(struct device_node *np,
const char *list_name, const char *cells_name, int index,
struct device_node **out_node, const void **out_args);

+extern int of_scan_aliases(void);
+extern int of_get_device_id(struct device_node *np, const char *name);
+
extern int of_machine_is_compatible(const char *compat);

extern int prom_add_property(struct device_node* np, struct property* prop);
--
Regards,
Shawn

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