[v3,1/3] 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...@nxp.com>
---
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 | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/soc/fsl/rcpm.c b/drivers/soc/fsl/rcpm.c
index 82c0ad5e663e..7f42b17d3f29 100644
--- a/drivers/soc/fsl/rcpm.c
+++ b/drivers/soc/fsl/rcpm.c
@@ -13,6 +13,8 @@
 #include <linux/slab.h>
 #include <linux/suspend.h>
 #include <linux/kernel.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
 
 #define RCPM_WAKEUP_CELL_MAX_SIZE      7
 
@@ -29,6 +31,9 @@ static int rcpm_pm_prepare(struct device *dev)
        struct rcpm             *rcpm;
        u32 value[RCPM_WAKEUP_CELL_MAX_SIZE + 1], tmp;
        int i, ret, idx;
+       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)
@@ -63,6 +68,22 @@ static int rcpm_pm_prepare(struct device *dev)
                                        tmp |= value[i + 1];
                                        iowrite32be(tmp, rcpm->ippdexpcr_base + 
i * 4);
                                }
+                               /* 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.
+                                */
+                               scfg_addr_regmap = 
syscon_regmap_lookup_by_phandle(np, "fsl,ippdexpcr-alt-addr");
+                               if (scfg_addr_regmap) {
+                                       if 
(of_property_read_u32_array(dev->of_node,
+                                           "fsl,ippdexpcr-alt-addr", 
reg_offset, rcpm->wakeup_cells + 1)) {
+                                               scfg_addr_regmap = NULL;
+                                               continue;
+                                       }
+                                       regmap_read(scfg_addr_regmap, 
reg_offset[i + 1], &reg_value);
+                                       /* Write value to register 
SCFG_SPARECR8 */
+                                       regmap_write(scfg_addr_regmap, 
reg_offset[i + 1], tmp | reg_value);
+                               }
                        }
                }
        } while (ws = wakeup_source_get_next(ws));
-- 
2.17.1