bcm27xx: import latest patches from the RPi foundation

bcm2708: boot tested on RPi B+ v1.2
bcm2709: boot tested on RPi 3B v1.2 and RPi 4B v1.1 4G
bcm2710: boot tested on RPi 3B v1.2
bcm2711: boot tested on RPi 4B v1.1 4G

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
(cherry-picked from commit f07e572f64)

1 files changed, 120 insertions, 0 deletions

diff --git a/target/linux/bcm27xx/patches-5.4/950-0944-rtc-rv3028-Write-BSM-and-TCE-TCR-to-EEPROM.patch b/target/linux/bcm27xx/patches-5.4/950-0944-rtc-rv3028-Write-BSM-and-TCE-TCR-to-EEPROM.patch
new file mode 100644
index 0000000000..54f3f4f367
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.4/950-0944-rtc-rv3028-Write-BSM-and-TCE-TCR-to-EEPROM.patch
@@ -0,0 +1,120 @@
+From ffc137a8949cd7859bdf139fa7a56b9dbdb4b2ce Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.com>
+Date: Fri, 15 May 2020 16:28:32 +0100
+Subject: [PATCH] rtc: rv3028: Write BSM and TCE/TCR to EEPROM
+
+Periodically the RV3028 refreshes registers from the EEPROM. When this
+happens, some settings that have only been committed to registers are
+lost. Change the handling of backup-switchover-mode and
+trickle-resistor-ohms to write the EEPROM instead (if something has
+changed), on the understanding that registers will be refreshed
+afterwards.
+
+See: https://github.com/raspberrypi/linux/issues/2912
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.com>
+---
+ drivers/rtc/rtc-rv3028.c | 60 ++++++++++++++++++++++++++++------------
+ 1 file changed, 43 insertions(+), 17 deletions(-)
+
+--- a/drivers/rtc/rtc-rv3028.c
++++ b/drivers/rtc/rtc-rv3028.c
+@@ -18,6 +18,7 @@
+ #include <linux/of_device.h>
+ #include <linux/regmap.h>
+ #include <linux/rtc.h>
++//#include "rtc-core.h"
+ 
+ #define RV3028_SEC			0x00
+ #define RV3028_MIN			0x01
+@@ -73,7 +74,7 @@
+ 
+ #define RV3028_BACKUP_TCE		BIT(5)
+ #define RV3028_BACKUP_TCR_MASK		GENMASK(1,0)
+-#define RV3028_BACKUP_BSM_MASK		0x0C
++#define RV3028_BACKUP_BSM_MASK		GENMASK(3,2)
+ 
+ #define OFFSET_STEP_PPT			953674
+ 
+@@ -601,7 +602,8 @@ static int rv3028_probe(struct i2c_clien
+ 	struct rv3028_data *rv3028;
+ 	int ret, status;
+ 	u32 ohms;
+-	u8 bsm;
++	u32 bsm;
++	u8 backup, backup_bits, backup_mask;
+ 	struct nvmem_config nvmem_cfg = {
+ 		.name = "rv3028_nvram",
+ 		.word_size = 1,
+@@ -673,16 +675,17 @@ static int rv3028_probe(struct i2c_clien
+ 	if (ret)
+ 		return ret;
+ 
++	backup_bits = 0;
++	backup_mask = 0;
++
+ 	/* setup backup switchover mode */
+-	if (!device_property_read_u8(&client->dev, "backup-switchover-mode",
+-				     &bsm))  {
++	dev_dbg(&client->dev, "Checking RTC backup switchover-mode\n");
++	if (!device_property_read_u32(&client->dev,
++				      "backup-switchover-mode",
++				      &bsm)) {
+ 		if (bsm <= 3) {
+-			ret = regmap_update_bits(rv3028->regmap, RV3028_BACKUP,
+-				RV3028_BACKUP_BSM_MASK,
+-				(bsm & 0x03) << 2);
+-
+-			if (ret)
+-				return ret;
++			backup_bits |= (u8)(bsm << 2);
++			backup_mask |= RV3028_BACKUP_BSM_MASK;
+ 		} else {
+ 			dev_warn(&client->dev, "invalid backup switchover mode value\n");
+ 		}
+@@ -698,15 +701,38 @@ static int rv3028_probe(struct i2c_clien
+ 				break;
+ 
+ 		if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
+-			ret = regmap_update_bits(rv3028->regmap, RV3028_BACKUP,
+-						 RV3028_BACKUP_TCE |
+-						 RV3028_BACKUP_TCR_MASK,
+-						 RV3028_BACKUP_TCE | i);
+-			if (ret)
+-				return ret;
++			backup_bits |= RV3028_BACKUP_TCE | i;
++			backup_mask |= RV3028_BACKUP_TCE |
++				RV3028_BACKUP_TCR_MASK;
+ 		} else {
+-			dev_warn(&client->dev, "invalid trickle resistor value\n");
++			dev_warn(&client->dev,
++				 "invalid trickle resistor value\n");
++		}
++	}
++
++	if (backup_mask) {
++		ret = rv3028_eeprom_read((void *)(rv3028->regmap),
++					 RV3028_BACKUP,
++					 (void *)&backup, 1);
++		if (!ret) {
++			/* Write EEPROM only if needed */
++			if ((backup & backup_mask) != backup_bits) {
++				backup = (backup & ~backup_mask) | backup_bits;
++				dev_dbg(&client->dev,
++					"Backup register doesn't match: EEPROM write required\n");
++				ret = rv3028_eeprom_write(
++					(void *)(rv3028->regmap),
++					RV3028_BACKUP, (void *)&backup, 1);
++			}
+ 		}
++
++		/* In the event of an EEPROM failure, update the register
++		   instead. */
++		if (ret)
++			ret = regmap_update_bits(rv3028->regmap, RV3028_BACKUP,
++						 backup_mask, backup_bits);
++		if (ret)
++			return ret;
+ 	}
+ 
+ 	ret = rtc_add_group(rv3028->rtc, &rv3028_attr_group);