[PATCH 2/5] soc: fsl: handle RCPM errata A-008646 on SoC LS1021A

[Ran Wang <ran.wang_1@xxxxxxx>]

From: Biwen Li <biwen.li@xxxxxxx>

Description:
	- Reading configuration register RCPM_IPPDEXPCR1
	  always return zero

Workaround:
	- Save register RCPM_IPPDEXPCR1's value to
	  register SCFG_SPARECR8.(uboot's psci also
	  need reading value from the register SCFG_SPARECR8
	  to set register RCPM_IPPDEXPCR1)

Impact:
	- FlexTimer module will cannot wakeup system in
	  deep sleep on SoC LS1021A

Signed-off-by: Biwen Li <biwen.li@xxxxxxx>
Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
---
 drivers/soc/fsl/rcpm.c | 42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/fsl/rcpm.c b/drivers/soc/fsl/rcpm.c
index a093dbe..e6354f5 100644
--- a/drivers/soc/fsl/rcpm.c
+++ b/drivers/soc/fsl/rcpm.c
@@ -2,7 +2,7 @@
 //
 // rcpm.c - Freescale QorIQ RCPM driver
 //
-// Copyright 2019 NXP
+// Copyright 2019-2020 NXP
 //
 // Author: Ran Wang <ran.wang_1@xxxxxxx>
 
@@ -13,6 +13,9 @@
 #include <linux/slab.h>
 #include <linux/suspend.h>
 #include <linux/kernel.h>
+#include <linux/acpi.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
 
 #define RCPM_WAKEUP_CELL_MAX_SIZE	7
 
@@ -37,6 +40,9 @@ static int rcpm_pm_prepare(struct device *dev)
 	struct device_node	*np = dev->of_node;
 	u32 value[RCPM_WAKEUP_CELL_MAX_SIZE + 1];
 	u32 setting[RCPM_WAKEUP_CELL_MAX_SIZE] = {0};
+	struct regmap *scfg_addr_regmap = NULL;
+	u32 reg_offset[2];
+	u32 reg_value = 0;
 
 	rcpm = dev_get_drvdata(dev);
 	if (!rcpm)
@@ -90,6 +96,40 @@ static int rcpm_pm_prepare(struct device *dev)
 			tmp |= ioread32be(address);
 			iowrite32be(tmp, address);
 		}
+		/*
+		 * Workaround of errata A-008646 on SoC LS1021A:
+		 * There is a bug of register ippdexpcr1.
+		 * Reading configuration register RCPM_IPPDEXPCR1
+		 * always return zero. So save ippdexpcr1's value
+		 * to register SCFG_SPARECR8.And the value of
+		 * ippdexpcr1 will be read from SCFG_SPARECR8.
+		 */
+		if (device_property_present(dev, "fsl,ippdexpcr1-alt-addr")) {
+			if (dev_of_node(dev)) {
+				scfg_addr_regmap = syscon_regmap_lookup_by_phandle(np,
+										   "fsl,ippdexpcr1-alt-addr");
+			} else if (is_acpi_node(dev->fwnode)) {
+				continue;
+			}
+
+			if (scfg_addr_regmap && (i == 1)) {
+				if (device_property_read_u32_array(dev,
+				    "fsl,ippdexpcr1-alt-addr",
+				    reg_offset,
+				    2)) {
+					scfg_addr_regmap = NULL;
+					continue;
+				}
+				/* Read value from register SCFG_SPARECR8 */
+				regmap_read(scfg_addr_regmap,
+					    reg_offset[1],
+					    &reg_value);
+				/* Write value to register SCFG_SPARECR8 */
+				regmap_write(scfg_addr_regmap,
+					     reg_offset[1],
+					     tmp | reg_value);
+			}
+		}
 	}
 
 	return 0;
-- 
2.7.4