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

[Ran Wang]

From: Biwen Li <biwen...@nxp.com>

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...@nxp.com>
Signed-off-by: Ran Wang <ran.wan...@nxp.com>
---
 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.wan...@nxp.com>
 
@@ -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