[RFC v8 net-next 06/16] pinctrl: microchip-sgpio: add ability to be used in a non-mmio configuration

[Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>]

There are a few Ocelot chips that can contain SGPIO logic, but can be
controlled externally. Specifically the VSC7511, 7512, 7513, and 7514. In
the externally controlled configurations these registers are not
memory-mapped.

Add support for these non-memory-mapped configurations.

Signed-off-by: Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>
---
 drivers/pinctrl/pinctrl-microchip-sgpio.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-microchip-sgpio.c b/drivers/pinctrl/pinctrl-microchip-sgpio.c
index 8953175c7e3e..88ab961cc5b9 100644
--- a/drivers/pinctrl/pinctrl-microchip-sgpio.c
+++ b/drivers/pinctrl/pinctrl-microchip-sgpio.c
@@ -20,6 +20,7 @@
 #include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/spinlock.h>
+#include <soc/mscc/ocelot.h>
 
 #include "core.h"
 #include "pinconf.h"
@@ -899,6 +900,7 @@ static int microchip_sgpio_probe(struct platform_device *pdev)
 	struct fwnode_handle *fwnode;
 	struct reset_control *reset;
 	struct sgpio_priv *priv;
+	struct resource *res;
 	struct clk *clk;
 	u32 __iomem *regs;
 	u32 val;
@@ -933,11 +935,23 @@ static int microchip_sgpio_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	regs = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(regs))
-		return PTR_ERR(regs);
+	regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(regs)) {
+		/*
+		 * Fall back to using IORESOURCE_REG, which is possible in an
+		 * MFD configuration
+		 */
+		res = platform_get_resource(pdev, IORESOURCE_REG, 0);
+		if (!res) {
+			dev_err(dev, "Failed to get resource\n");
+			return -ENODEV;
+		}
+
+		priv->regs = ocelot_init_regmap_from_resource(dev, res);
+	} else {
+		priv->regs = devm_regmap_init_mmio(dev, regs, &regmap_config);
+	}
 
-	priv->regs = devm_regmap_init_mmio(dev, regs, &regmap_config);
 	if (IS_ERR(priv->regs))
 		return PTR_ERR(priv->regs);
 
-- 
2.25.1