[v5 1/3] soc: fsl: handle RCPM errata A-008646 on SoC LS1021A

[Biwen Li]

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>
---
Change in v5:
	- update the patch, because of rcpm driver has updated.

Change in v4:
	- rename property name
	  fsl,ippdexpcr-alt-addr -> fsl,ippdexpcr1-alt-addr

Change in v3:
	- update commit message
	- rename property name
	  fsl,rcpm-scfg -> fsl,ippdexpcr-alt-addr

Change in v2:
  	- fix stype problems

 drivers/soc/fsl/rcpm.c | 47 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 45 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/fsl/rcpm.c b/drivers/soc/fsl/rcpm.c
index a093dbe6d2cb..775c618f0456 100644
--- a/drivers/soc/fsl/rcpm.c
+++ b/drivers/soc/fsl/rcpm.c
@@ -6,13 +6,16 @@
 //
 // Author: Ran Wang <ran.wang_1@xxxxxxx>
 
+#include <linux/acpi.h>
 #include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
-#include <linux/platform_device.h>
 #include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
-#include <linux/kernel.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[RCPM_WAKEUP_CELL_MAX_SIZE + 1];
+	u32 reg_value = 0;
 
 	rcpm = dev_get_drvdata(dev);
 	if (!rcpm)
@@ -90,6 +96,43 @@ 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)) {
+				dev_err(dev, "not support acpi for rcpm\n");
+				continue;
+			}
+
+			if (scfg_addr_regmap && (i == 1)) {
+				if (device_property_read_u32_array(dev,
+				    "fsl,ippdexpcr1-alt-addr",
+				    reg_offset,
+				    1 + sizeof(u64)/sizeof(u32))) {
+					scfg_addr_regmap = NULL;
+					continue;
+				}
+				/* Read value from register SCFG_SPARECR8 */
+				regmap_read(scfg_addr_regmap,
+					    (u32)(((u64)(reg_offset[1] << (sizeof(u32) * 8) |
+					    reg_offset[2])) & 0xffffffff),
+					    &reg_value);
+				/* Write value to register SCFG_SPARECR8 */
+				regmap_write(scfg_addr_regmap,
+					     (u32)(((u64)(reg_offset[1] << (sizeof(u32) * 8) |
+					     reg_offset[2])) & 0xffffffff),
+					     tmp | reg_value);
+			}
+		}
 	}
 
 	return 0;
-- 
2.17.1