clk: ti: fix ti_clk_get_reg_addr error handling

There is a case where NULL can be a valid return value for
ti_clk_get_reg_addr, specifically the case where both the provider index
and register offsets are zero. In this case, the current error checking
against a NULL pointer will fail. Thus, change the API to return a
ERR_PTR value in an error case, and change all the users of this API to
check against IS_ERR instead.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Michael Turquette <mturquette@linaro.org>

drivers/clk/ti/apll.c

@@ -203,7 +203,7 @@ static void __init of_dra7_apll_setup(struct device_node *node)
 	ad->control_reg = ti_clk_get_reg_addr(node, 0);
 	ad->idlest_reg = ti_clk_get_reg_addr(node, 1);
 
-	if (!ad->control_reg || !ad->idlest_reg)
+	if (IS_ERR(ad->control_reg) || IS_ERR(ad->idlest_reg))
 		goto cleanup;
 
 	ad->idlest_mask = 0x1;
@@ -384,7 +384,8 @@ static void __init of_omap2_apll_setup(struct device_node *node)
 	ad->autoidle_reg = ti_clk_get_reg_addr(node, 1);
 	ad->idlest_reg = ti_clk_get_reg_addr(node, 2);
 
-	if (!ad->control_reg || !ad->autoidle_reg || !ad->idlest_reg)
+	if (IS_ERR(ad->control_reg) || IS_ERR(ad->autoidle_reg) ||
+	    IS_ERR(ad->idlest_reg))
 		goto cleanup;
 
 	clk = clk_register(NULL, &clk_hw->hw);

drivers/clk/ti/autoidle.c

@@ -119,7 +119,7 @@ int __init of_ti_clk_autoidle_setup(struct device_node *node)
 	clk->name = node->name;
 	clk->reg = ti_clk_get_reg_addr(node, 0);
 
-	if (!clk->reg) {
+	if (IS_ERR(clk->reg)) {
 		kfree(clk);
 		return -EINVAL;
 	}

drivers/clk/ti/clk.c

@@ -103,7 +103,8 @@ int __init ti_clk_retry_init(struct device_node *node, struct clk_hw *hw,
  * @index: register index from the clock node
  *
  * Builds clock register address from device tree information. This
- * is a struct of type clk_omap_reg.
+ * is a struct of type clk_omap_reg. Returns a pointer to the register
+ * address, or a pointer error value in failure.
  */
 void __iomem *ti_clk_get_reg_addr(struct device_node *node, int index)
 {
@@ -121,14 +122,14 @@ void __iomem *ti_clk_get_reg_addr(struct device_node *node, int index)
 
 	if (i == CLK_MAX_MEMMAPS) {
 		pr_err("clk-provider not found for %s!\n", node->name);
-		return NULL;
+		return ERR_PTR(-ENOENT);
 	}
 
 	reg->index = i;
 
 	if (of_property_read_u32_index(node, "reg", index, &val)) {
 		pr_err("%s must have reg[%d]!\n", node->name, index);
-		return NULL;
+		return ERR_PTR(-EINVAL);
 	}
 
 	reg->offset = val;

drivers/clk/ti/divider.c

@@ -530,8 +530,8 @@ static int __init ti_clk_divider_populate(struct device_node *node,
 	u32 val;
 
 	*reg = ti_clk_get_reg_addr(node, 0);
-	if (!*reg)
-		return -EINVAL;
+	if (IS_ERR(*reg))
+		return PTR_ERR(*reg);
 
 	if (!of_property_read_u32(node, "ti,bit-shift", &val))
 		*shift = val;

drivers/clk/ti/dpll.c

@@ -390,18 +390,18 @@ static void __init of_ti_dpll_setup(struct device_node *node,
 #endif
 	} else {
 		dd->idlest_reg = ti_clk_get_reg_addr(node, 1);
-		if (!dd->idlest_reg)
+		if (IS_ERR(dd->idlest_reg))
 			goto cleanup;
 
 		dd->mult_div1_reg = ti_clk_get_reg_addr(node, 2);
 	}
 
-	if (!dd->control_reg || !dd->mult_div1_reg)
+	if (IS_ERR(dd->control_reg) || IS_ERR(dd->mult_div1_reg))
 		goto cleanup;
 
 	if (dd->autoidle_mask) {
 		dd->autoidle_reg = ti_clk_get_reg_addr(node, 3);
-		if (!dd->autoidle_reg)
+		if (IS_ERR(dd->autoidle_reg))
 			goto cleanup;
 	}
 

drivers/clk/ti/gate.c

@@ -225,7 +225,7 @@ static void __init _of_ti_gate_clk_setup(struct device_node *node,
 
 	if (ops != &omap_gate_clkdm_clk_ops) {
 		reg = ti_clk_get_reg_addr(node, 0);
-		if (!reg)
+		if (IS_ERR(reg))
 			return;
 
 		if (!of_property_read_u32(node, "ti,bit-shift", &val))
@@ -264,7 +264,7 @@ _of_ti_composite_gate_clk_setup(struct device_node *node,
 		return;
 
 	gate->enable_reg = ti_clk_get_reg_addr(node, 0);
-	if (!gate->enable_reg)
+	if (IS_ERR(gate->enable_reg))
 		goto cleanup;
 
 	of_property_read_u32(node, "ti,bit-shift", &val);

drivers/clk/ti/interface.c

@@ -111,7 +111,7 @@ static void __init _of_ti_interface_clk_setup(struct device_node *node,
 	u32 val;
 
 	reg = ti_clk_get_reg_addr(node, 0);
-	if (!reg)
+	if (IS_ERR(reg))
 		return;
 
 	if (!of_property_read_u32(node, "ti,bit-shift", &val))

drivers/clk/ti/mux.c

@@ -210,7 +210,7 @@ static void of_mux_clk_setup(struct device_node *node)
 
 	reg = ti_clk_get_reg_addr(node, 0);
 
-	if (!reg)
+	if (IS_ERR(reg))
 		goto cleanup;
 
 	of_property_read_u32(node, "ti,bit-shift", &shift);
@@ -283,7 +283,7 @@ static void __init of_ti_composite_mux_clk_setup(struct device_node *node)
 
 	mux->reg = ti_clk_get_reg_addr(node, 0);
 
-	if (!mux->reg)
+	if (IS_ERR(mux->reg))
 		goto cleanup;
 
 	if (!of_property_read_u32(node, "ti,bit-shift", &val))