Merge tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

Pull ARM SoC driver updates from Arnd Bergmann:
 "Driver updates for ARM SoCs, including a couple of newly added
  drivers:

   - A new driver for the power management controller on TI Keystone

   - Support for the prerelease "SCPI" firmware protocol that ended up
     being shipped by Amlogic in their GXBB SoC.

   - A soc_device can now be matched using a glob from inside the
     kernel, when another driver wants to know the specific chip it is
     running on and cannot find out from DT, firmware or hardware.

   - Renesas SoCs now support identification through the soc_device
     interface, both in user space and kernel.

   - Renesas r8a7743 and r8a7745 gain support for their system
     controller

   - A new checking module for the ARM "PSCI" (not to be confused with
     "SCPI" mentioned above) firmware interface.

   - A new driver for the Tegra GMI memory interface

   - Support for the Tegra firmware interfaces with their power
     management controllers

  As usual, the updates for the reset controller framework are merged
  here, as they tend to touch multiple SoCs as well, including a new
  driver for the Oxford (now Broadcom) OX820 chip and the Tegra bpmp
  interface.

  The existing drivers for Atmel, Qualcomm, NVIDIA, TI Davinci, and
  Rockchips SoCs see some further updates"

* tag 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (76 commits)
  misc: sram: remove useless #ifdef
  drivers: psci: Allow PSCI node to be disabled
  drivers: psci: PSCI checker module
  soc: renesas: Identify SoC and register with the SoC bus
  firmware: qcom: scm: Return PTR_ERR when devm_clk_get fails
  firmware: qcom: scm: Remove core, iface and bus clocks dependency
  dt-bindings: firmware: scm: Add MSM8996 DT bindings
  memory: da8xx-ddrctl: drop the call to of_flat_dt_get_machine_name()
  bus: da8xx-mstpri: drop the call to of_flat_dt_get_machine_name()
  ARM: shmobile: Document DT bindings for Product Register
  soc: renesas: rcar-sysc: add R8A7745 support
  reset: Add Tegra BPMP reset driver
  dt-bindings: firmware: Allow child nodes inside the Tegra BPMP
  dt-bindings: Add power domains to Tegra BPMP firmware
  firmware: tegra: Add BPMP support
  firmware: tegra: Add IVC library
  dt-bindings: firmware: Add bindings for Tegra BPMP
  mailbox: tegra-hsp: Use after free in tegra_hsp_remove_doorbells()
  mailbox: Add Tegra HSP driver
  firmware: arm_scpi: add support for pre-v1.0 SCPI compatible
  ...

1 files changed, 37 insertions, 6 deletions

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index b8ae1dbd4c17..10368ed8fd13 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -32,6 +32,9 @@ static LIST_HEAD(reset_controller_list);
  * @refcnt: Number of gets of this reset_control
  * @shared: Is this a shared (1), or an exclusive (0) reset_control?
  * @deassert_cnt: Number of times this reset line has been deasserted
+ * @triggered_count: Number of times this reset line has been reset. Currently
+ *                   only used for shared resets, which means that the value
+ *                   will be either 0 or 1.
  */
 struct reset_control {
 	struct reset_controller_dev *rcdev;
@@ -40,6 +43,7 @@ struct reset_control {
 	unsigned int refcnt;
 	int shared;
 	atomic_t deassert_count;
+	atomic_t triggered_count;
 };
 
 /**
@@ -134,18 +138,35 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register);
  * reset_control_reset - reset the controlled device
  * @rstc: reset controller
  *
- * Calling this on a shared reset controller is an error.
+ * On a shared reset line the actual reset pulse is only triggered once for the
+ * lifetime of the reset_control instance: for all but the first caller this is
+ * a no-op.
+ * Consumers must not use reset_control_(de)assert on shared reset lines when
+ * reset_control_reset has been used.
  */
 int reset_control_reset(struct reset_control *rstc)
 {
-	if (WARN_ON(IS_ERR_OR_NULL(rstc)) ||
-	    WARN_ON(rstc->shared))
+	int ret;
+
+	if (WARN_ON(IS_ERR_OR_NULL(rstc)))
 		return -EINVAL;
 
-	if (rstc->rcdev->ops->reset)
-		return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
+	if (!rstc->rcdev->ops->reset)
+		return -ENOTSUPP;
 
-	return -ENOTSUPP;
+	if (rstc->shared) {
+		if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
+			return -EINVAL;
+
+		if (atomic_inc_return(&rstc->triggered_count) != 1)
+			return 0;
+	}
+
+	ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
+	if (rstc->shared && !ret)
+		atomic_dec(&rstc->triggered_count);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(reset_control_reset);
 
@@ -159,6 +180,8 @@ EXPORT_SYMBOL_GPL(reset_control_reset);
  *
  * For shared reset controls a driver cannot expect the hw's registers and
  * internal state to be reset, but must be prepared for this to happen.
+ * Consumers must not use reset_control_reset on shared reset lines when
+ * reset_control_(de)assert has been used.
  */
 int reset_control_assert(struct reset_control *rstc)
 {
@@ -169,6 +192,9 @@ int reset_control_assert(struct reset_control *rstc)
 		return -ENOTSUPP;
 
 	if (rstc->shared) {
+		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
+			return -EINVAL;
+
 		if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
 			return -EINVAL;
 
@@ -185,6 +211,8 @@ EXPORT_SYMBOL_GPL(reset_control_assert);
  * @rstc: reset controller
  *
  * After calling this function, the reset is guaranteed to be deasserted.
+ * Consumers must not use reset_control_reset on shared reset lines when
+ * reset_control_(de)assert has been used.
  */
 int reset_control_deassert(struct reset_control *rstc)
 {
@@ -195,6 +223,9 @@ int reset_control_deassert(struct reset_control *rstc)
 		return -ENOTSUPP;
 
 	if (rstc->shared) {
+		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
+			return -EINVAL;
+
 		if (atomic_inc_return(&rstc->deassert_count) != 1)
 			return 0;
 	}