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Message-ID: <20251208221319.1524888-5-vvidwans@nvidia.com>
Date: Mon, 8 Dec 2025 22:13:14 +0000
From: Vedashree Vidwans <vvidwans@...dia.com>
To: <salman.nabi@....com>, <sudeep.holla@....com>, <andre.przywara@....com>,
<lpieralisi@...nel.org>, <mark.rutland@....com>
CC: <ardb@...nel.org>, <chao.gao@...el.com>,
<linux-arm-kernel@...ts.infradead.org>, <linux-coco@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>, <sdonthineni@...dia.com>,
<vsethi@...dia.com>, <vwadekar@...dia.com>, Vedashree Vidwans
<vvidwans@...dia.com>
Subject: [RFC PATCH 4/5] firmware: smccc: register as platform driver
- Update driver to be in-built kernel module. This will ensure driver is
installed in kernel and would not require any user intervention.
- Register the LFA driver as a platform driver corresponding to
'armhf000' device. The driver will be invoked when the device is
detected on a platform.
- Add functionality to register LFA interrupt in the driver probe().
This LFA IRQ number will be retrived from the LFA device node.
- On IRQ, driver will query FW component details and trigger activation
of capable and pending FW component. The driver will loop to update FW
component details after every successful FW component activation.
- Mutex synchronization is implemented to avoid concurrent LFA updates
through interrupt and sysfs interfaces.
Device node snippet from LFA spec[1]:
fwu0 {
compatible = "arm,armhf000";
memory-region = <&fwu_payload>;
interrupt-parent = <&ic>;
interrupts = <0 100 1>; // SPI, Interrupt #100, Edge Rising
};
[1] https://developer.arm.com/documentation/den0147/latest/
Signed-off-by: Vedashree Vidwans <vvidwans@...dia.com>
---
drivers/firmware/smccc/Kconfig | 3 +-
drivers/firmware/smccc/lfa_fw.c | 124 +++++++++++++++++++++++++++++++-
2 files changed, 125 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/smccc/Kconfig b/drivers/firmware/smccc/Kconfig
index 48b98c14f770..c21be43fbfed 100644
--- a/drivers/firmware/smccc/Kconfig
+++ b/drivers/firmware/smccc/Kconfig
@@ -25,8 +25,9 @@ config ARM_SMCCC_SOC_ID
platforms providing some sysfs information about the SoC variant.
config ARM_LFA
- tristate "Arm Live Firmware activation support"
+ bool "Arm Live Firmware activation support"
depends on HAVE_ARM_SMCCC_DISCOVERY
+ default y
help
Include support for triggering Live Firmware Activation, which
allows to upgrade certain firmware components without a reboot.
diff --git a/drivers/firmware/smccc/lfa_fw.c b/drivers/firmware/smccc/lfa_fw.c
index 0e420cefa260..24916fc53420 100644
--- a/drivers/firmware/smccc/lfa_fw.c
+++ b/drivers/firmware/smccc/lfa_fw.c
@@ -19,7 +19,12 @@
#include <linux/nmi.h>
#include <linux/ktime.h>
#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+#define DRIVER_NAME "ARM_LFA"
#define LFA_ERROR_STRING(name) \
[name] = #name
#undef pr_fmt
@@ -129,6 +134,7 @@ static const struct fw_image_uuid {
};
static struct kobject *lfa_dir;
+static DEFINE_MUTEX(lfa_lock);
static int get_nr_lfa_components(void)
{
@@ -374,17 +380,23 @@ static ssize_t activate_store(struct kobject *kobj, struct kobj_attribute *attr,
image_attrs[LFA_ATTR_ACTIVATE]);
int ret;
+ if (!mutex_trylock(&lfa_lock)) {
+ pr_err("Mutex locked, try again");
+ return -EAGAIN;
+ }
+
ret = activate_fw_image(attrs);
if (ret) {
pr_err("Firmware activation failed: %s\n",
lfa_error_strings[-ret]);
-
+ mutex_unlock(&lfa_lock);
return -ECANCELED;
}
pr_info("Firmware activation succeeded\n");
/* TODO: refresh image flags here*/
+ mutex_unlock(&lfa_lock);
return count;
}
@@ -510,6 +522,106 @@ static int create_fw_images_tree(void)
return 0;
}
+static irqreturn_t lfa_irq_thread(int irq, void *data)
+{
+ struct image_props *attrs = NULL;
+ int ret;
+ int num_of_components, curr_component;
+
+ mutex_lock(&lfa_lock);
+
+ /*
+ * As per LFA spec, after activation of a component, the caller
+ * is expected to re-enumerate the component states (using
+ * LFA_GET_INFO then LFA_GET_INVENTORY).
+ * Hence we need an unconditional loop.
+ */
+
+ do {
+ /* TODO: refresh image flags here */
+ /* If refresh fails goto exit_unlock */
+
+ /* Initialize counters to track list traversal */
+ num_of_components = get_nr_lfa_components();
+ curr_component = 0;
+
+ /* Execute PRIME and ACTIVATE for activable FW component */
+ list_for_each_entry(attrs, &lfa_fw_images, image_node) {
+ curr_component++;
+ if ((!attrs->activation_capable) || (!attrs->activation_pending)) {
+ /* LFA not applicable for this FW component */
+ continue;
+ }
+
+ ret = activate_fw_image(attrs);
+ if (ret) {
+ pr_err("Firmware %s activation failed: %s\n",
+ attrs->image_name, lfa_error_strings[-ret]);
+ goto exit_unlock;
+ }
+
+ pr_info("Firmware %s activation succeeded", attrs->image_name);
+ /* Refresh FW component details */
+ break;
+ }
+ } while (curr_component < num_of_components);
+
+ /* TODO: refresh image flags here */
+ /* If refresh fails goto exit_unlock */
+
+exit_unlock:
+ mutex_unlock(&lfa_lock);
+ return IRQ_HANDLED;
+}
+
+static int __init lfa_probe(struct platform_device *pdev)
+{
+ int err;
+ unsigned int irq;
+
+ err = platform_get_irq_byname_optional(pdev, "fw-store-updated-interrupt");
+ if (err < 0)
+ err = platform_get_irq(pdev, 0);
+ if (err < 0) {
+ pr_err("Interrupt not found, functionality will be unavailable.");
+
+ /* Bail out without failing the driver. */
+ return 0;
+ }
+ irq = err;
+
+ err = request_threaded_irq(irq, NULL, lfa_irq_thread, IRQF_ONESHOT, DRIVER_NAME, NULL);
+ if (err != 0) {
+ pr_err("Interrupt setup failed, functionality will be unavailable.");
+
+ /* Bail out without failing the driver. */
+ return 0;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id lfa_of_ids[] = {
+ { .compatible = "arm,armhf000", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, lfa_of_ids);
+
+static const struct acpi_device_id lfa_acpi_ids[] = {
+ {"ARMHF000"},
+ {},
+};
+MODULE_DEVICE_TABLE(acpi, lfa_acpi_ids);
+
+static struct platform_driver lfa_driver = {
+ .probe = lfa_probe,
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = lfa_of_ids,
+ .acpi_match_table = ACPI_PTR(lfa_acpi_ids),
+ },
+};
+
static int __init lfa_init(void)
{
struct arm_smccc_1_2_regs reg = { 0 };
@@ -536,22 +648,32 @@ static int __init lfa_init(void)
pr_info("Arm Live Firmware Activation (LFA): detected v%ld.%ld\n",
reg.a0 >> 16, reg.a0 & 0xffff);
+ err = platform_driver_register(&lfa_driver);
+ if (err < 0)
+ pr_err("Platform driver register failed");
+
lfa_dir = kobject_create_and_add("lfa", firmware_kobj);
if (!lfa_dir)
return -ENOMEM;
+ mutex_lock(&lfa_lock);
err = create_fw_images_tree();
if (err != 0)
kobject_put(lfa_dir);
+ mutex_unlock(&lfa_lock);
return err;
}
module_init(lfa_init);
static void __exit lfa_exit(void)
{
+ mutex_lock(&lfa_lock);
clean_fw_images_tree();
+ mutex_unlock(&lfa_lock);
+
kobject_put(lfa_dir);
+ platform_driver_unregister(&lfa_driver);
}
module_exit(lfa_exit);
--
2.43.0
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