Re: [PATCH] drivers/memory/Kconfig: Add CONFIG_OF dependency

[Boris Brezillon <boris.brezillon@bootlin.com>]

+Arnd, Rob and the DT ML.

On Sat, 21 Jul 2018 14:53:47 -0700
Randy Dunlap <rdunlap@infradead.org> wrote:

> On 07/21/2018 01:00 PM, Anders Roxell wrote:
> > JZ4780_NEMC doesn't depend on OF, and if OF isn't enabled we get this
> > error:
> > drivers/memory/jz4780-nemc.c: In function ‘jz4780_nemc_num_banks’:
> > drivers/memory/jz4780-nemc.c:72:10: error: implicit declaration of
> >  function ‘of_read_number’; did you mean ‘down_read_nested’?
> >  [-Werror=implicit-function-declaration]
> >    bank = of_read_number(prop, 1);
> >           ^~~~~~~~~~~~~~
> >           down_read_nested

Looks like of.h defines stubs so that people can compile-test without
CONFIG_OF selected. Maybe we should move of_read_number() and
of_read_ulong() out of the #ifdef CONFIG_OF section.

Alternatively, we could patch jz4780-nemc.c to not use of_read_number
and instead rely on of_read_property_u32_index() +
of_property_count_elems_of_size() + of_n_{addr,size}_cells():

--->8---
diff --git a/drivers/memory/jz4780-nemc.c b/drivers/memory/jz4780-nemc.c
index bcf06adefc96..9ad7abc6983a 100644
--- a/drivers/memory/jz4780-nemc.c
+++ b/drivers/memory/jz4780-nemc.c
@@ -63,14 +63,21 @@ struct jz4780_nemc {
  */
 unsigned int jz4780_nemc_num_banks(struct device *dev)
 {
-       const __be32 *prop;
-       unsigned int bank, count = 0;
        unsigned long referenced = 0;
-       int i = 0;
-
-       while ((prop = of_get_address(dev->of_node, i++, NULL, NULL))) {
-               bank = of_read_number(prop, 1);
-               if (!(referenced & BIT(bank))) {
+       int nelems, elemsize, i = 0;
+       unsigned int count = 0;
+
+       /* #address-cells = 2 and #size-cells = 1, hence  */
+       elemsize = of_n_addr_cells(dev->of_node) +
+                  of_n_size_cells(dev->of_node);
+       nelems = of_property_count_elems_of_size(dev->of_node, "reg", elemsize);
+       for (i = 0; i < nelems; i++) {
+               u32 bank;
+
+               if (!of_property_read_u32_index(dev->of_node, "reg",
+                                               i * elemsize, &bank) &&
+                   bank >= 1 && bank < JZ4780_NEMC_NUM_BANKS &&
+                   !(referenced & BIT(bank))) {
                        referenced |= BIT(bank);
                        count++;
                }
@@ -269,10 +276,9 @@ static int jz4780_nemc_probe(struct platform_device *pdev)
        struct jz4780_nemc *nemc;
        struct resource *res;
        struct device_node *child;
-       const __be32 *prop;
-       unsigned int bank;
        unsigned long referenced;
        int i, ret;
+       u32 bank;
 
        nemc = devm_kzalloc(dev, sizeof(*nemc), GFP_KERNEL);
        if (!nemc)
@@ -316,10 +322,27 @@ static int jz4780_nemc_probe(struct platform_device *pdev)
         * registered for it.
         */
        for_each_child_of_node(nemc->dev->of_node, child) {
+               int nelems, elemsize;
+
                referenced = 0;
                i = 0;
-               while ((prop = of_get_address(child, i++, NULL, NULL))) {
-                       bank = of_read_number(prop, 1);
+               elemsize = of_n_addr_cells(dev->of_node) +
+                          of_n_size_cells(dev->of_node);
+               nelems = of_property_count_elems_of_size(dev->of_node, "reg",
+                                                        elemsize);
+               for (i = 0; i < nelems; i++) {
+                       u32 bank;
+
+                       ret = of_property_read_u32_index(dev->of_node, "reg",
+                                                        i * elemsize, &bank);
+                       if (ret) {
+                               dev_err(nemc->dev,
+                                       "failed to read bank %d of %pOF (err = %d)\n",
+                                       i, child, ret);
+                               referenced = 0;
+                               break;
+                       }
+
                        if (bank < 1 || bank >= JZ4780_NEMC_NUM_BANKS) {
                                dev_err(nemc->dev,
                                        "%pOF requests invalid bank %u\n",