gpio/omap: don't use linear domain mapping for OMAP1

Commit ede4d7a ("gpio/omap: convert gpio irq domain to linear mapping")
converted the OMAP GPIO driver to use a linear mapping for the GPIO IRQ
domain instead of using a legacy mapping. Not using a legacy mapping has
a number of benefits but it requires the platform to support SPARSE_IRQ
which currently is not supported on OMAP1.

So this change caused a regression on OMAP1 platforms [1].

Since this issue is not present on all OMAP2+ platforms, there is no need to
revert the driver to use legacy domain mapping for all the platforms.

[1]: http://www.mail-archive.com/linux-omap@vger.kernel.org/msg89005.html

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/gpio/gpio-omap.c

@@ -1094,6 +1094,9 @@ static int omap_gpio_probe(struct platform_device *pdev)
 	const struct omap_gpio_platform_data *pdata;
 	struct resource *res;
 	struct gpio_bank *bank;
+#ifdef CONFIG_ARCH_OMAP1
+	int irq_base;
+#endif
 
 	match = of_match_device(of_match_ptr(omap_gpio_match), dev);
 
@@ -1135,11 +1138,28 @@ static int omap_gpio_probe(struct platform_device *pdev)
 				pdata->get_context_loss_count;
 	}
 
+#ifdef CONFIG_ARCH_OMAP1
+	/*
+	 * REVISIT: Once we have OMAP1 supporting SPARSE_IRQ, we can drop
+	 * irq_alloc_descs() and irq_domain_add_legacy() and just use a
+	 * linear IRQ domain mapping for all OMAP platforms.
+	 */
+	irq_base = irq_alloc_descs(-1, 0, bank->width, 0);
+	if (irq_base < 0) {
+		dev_err(dev, "Couldn't allocate IRQ numbers\n");
+		return -ENODEV;
+	}
 
+	bank->domain = irq_domain_add_legacy(node, bank->width, irq_base,
+					     0, &irq_domain_simple_ops, NULL);
+#else
 	bank->domain = irq_domain_add_linear(node, bank->width,
 					     &irq_domain_simple_ops, NULL);
-	if (!bank->domain)
+#endif
+	if (!bank->domain) {
+		dev_err(dev, "Couldn't register an IRQ domain\n");
 		return -ENODEV;
+	}
 
 	if (bank->regs->set_dataout && bank->regs->clr_dataout)
 		bank->set_dataout = _set_gpio_dataout_reg;