hwspinlock: qcom: Allow mmio usage in addition to syscon

In modern Qualcomm platforms the mutex region of the TCSR is forked off
into its own block, all with a offset of 0 and stride of 4096, and in
some of these platforms no other registers in this region is accessed
from Linux.

So add support for directly memory mapping this register space, to avoid
the need to represent this block using a syscon.

Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200622075956.171058-4-bjorn.andersson@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/hwspinlock/qcom_hwspinlock.c

@@ -70,41 +70,79 @@ static const struct of_device_id qcom_hwspinlock_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, qcom_hwspinlock_of_match);
 
+static struct regmap *qcom_hwspinlock_probe_syscon(struct platform_device *pdev,
+						   u32 *base, u32 *stride)
+{
+	struct device_node *syscon;
+	struct regmap *regmap;
+	int ret;
+
+	syscon = of_parse_phandle(pdev->dev.of_node, "syscon", 0);
+	if (!syscon)
+		return ERR_PTR(-ENODEV);
+
+	regmap = syscon_node_to_regmap(syscon);
+	of_node_put(syscon);
+	if (IS_ERR(regmap))
+		return regmap;
+
+	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1, base);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "no offset in syscon\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 2, stride);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "no stride syscon\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	return regmap;
+}
+
+static const struct regmap_config tcsr_mutex_config = {
+	.reg_bits		= 32,
+	.reg_stride		= 4,
+	.val_bits		= 32,
+	.max_register		= 0x40000,
+	.fast_io		= true,
+};
+
+static struct regmap *qcom_hwspinlock_probe_mmio(struct platform_device *pdev,
+						 u32 *offset, u32 *stride)
+{
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+
+	/* All modern platform has offset 0 and stride of 4k */
+	*offset = 0;
+	*stride = 0x1000;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return ERR_CAST(base);
+
+	return devm_regmap_init_mmio(dev, base, &tcsr_mutex_config);
+}
+
 static int qcom_hwspinlock_probe(struct platform_device *pdev)
 {
 	struct hwspinlock_device *bank;
-	struct device_node *syscon;
 	struct reg_field field;
 	struct regmap *regmap;
 	size_t array_size;
 	u32 stride;
 	u32 base;
-	int ret;
 	int i;
 
-	syscon = of_parse_phandle(pdev->dev.of_node, "syscon", 0);
-	if (!syscon) {
-		dev_err(&pdev->dev, "no syscon property\n");
-		return -ENODEV;
-	}
+	regmap = qcom_hwspinlock_probe_syscon(pdev, &base, &stride);
+	if (IS_ERR(regmap) && PTR_ERR(regmap) == -ENODEV)
+		regmap = qcom_hwspinlock_probe_mmio(pdev, &base, &stride);
 
-	regmap = syscon_node_to_regmap(syscon);
-	of_node_put(syscon);
 	if (IS_ERR(regmap))
 		return PTR_ERR(regmap);
 
-	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1, &base);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "no offset in syscon\n");
-		return -EINVAL;
-	}
-
-	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 2, &stride);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "no stride syscon\n");
-		return -EINVAL;
-	}
-
 	array_size = QCOM_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
 	bank = devm_kzalloc(&pdev->dev, sizeof(*bank) + array_size, GFP_KERNEL);
 	if (!bank)