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Message-ID: <20251011010251.50c8be14@minigeek.lan>
Date: Sat, 11 Oct 2025 01:02:51 +0100
From: Andre Przywara <andre.przywara@....com>
To: Vedashree Vidwans <vvidwans@...dia.com>
Cc: <salman.nabi@....com>, <lpieralisi@...nel.org>, <mark.rutland@....com>,
<sudeep.holla@....com>, <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>
Subject: Re: [RFC PATCH 1/3] firmware: smccc: LFA: use smcc 1.2
On Wed, 8 Oct 2025 19:09:05 +0000
Vedashree Vidwans <vvidwans@...dia.com> wrote:
Hi Vedashree,
> Update driver to use SMCCC 1.2+ version as mentioned in the LFA spec.
ah, right, good catch, one call is using x4, so this must be the v1.2
calling convention.
Just one small thing below...
> Signed-off-by: Vedashree Vidwans <vvidwans@...dia.com>
> ---
> drivers/firmware/smccc/lfa_fw.c | 80 +++++++++++++++++++++++----------
> 1 file changed, 56 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/firmware/smccc/lfa_fw.c b/drivers/firmware/smccc/lfa_fw.c
> index 1f333237271d8..49f7feb6a211b 100644
> --- a/drivers/firmware/smccc/lfa_fw.c
> +++ b/drivers/firmware/smccc/lfa_fw.c
> @@ -117,9 +117,13 @@ static struct kobject *lfa_dir;
>
> static int get_nr_lfa_components(void)
> {
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
>
> - arm_smccc_1_1_invoke(LFA_1_0_FN_GET_INFO, 0x0, &res);
> + args.a0 = LFA_1_0_FN_GET_INFO;
> + args.a1 = 0; /* lfa_info_selector = 0 */
> +
> + arm_smccc_1_2_invoke(&args, &res);
I wonder if we can share the same struct for both request and reply?
arm_smccc_1_2_invoke(&args, &args);
Looks like a lot of stack space used for just a few registers.
Same for the other occasions where we just do the smc once.
Cheers,
Andre.
> if (res.a0 != LFA_SUCCESS)
> return res.a0;
>
> @@ -129,20 +133,23 @@ static int get_nr_lfa_components(void)
> static int call_lfa_activate(void *data)
> {
> struct image_props *attrs = data;
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
> +
> + args.a0 = LFA_1_0_FN_ACTIVATE;
> + args.a1 = attrs->fw_seq_id; /* fw_seq_id under consideration */
> + /*
> + * As we do not support updates requiring a CPU reset (yet),
> + * we pass 0 in args.a3 and args.a4, holding the entry point and context
> + * ID respectively.
> + * We want to force CPU rendezvous if either cpu_rendezvous or
> + * cpu_rendezvous_forced is set. The flag value is flipped as
> + * it is called skip_cpu_rendezvous in the spec.
> + */
> + args.a2 = !(attrs->cpu_rendezvous_forced || attrs->cpu_rendezvous);
>
> do {
> - /*
> - * As we do not support updates requiring a CPU reset (yet),
> - * we pass 0 in x3 and x4, holding the entry point and context
> - * ID respectively.
> - * We want to force CPU rendezvous if either cpu_rendezvous or
> - * cpu_rendezvous_forced is set. The flag value is flipped as
> - * it is called skip_cpu_rendezvous in the spec.
> - */
> - arm_smccc_1_1_invoke(LFA_1_0_FN_ACTIVATE, attrs->fw_seq_id,
> - !(attrs->cpu_rendezvous_forced || attrs->cpu_rendezvous),
> - 0, 0, &res);
> + arm_smccc_1_2_invoke(&args, &res);
> } while (res.a0 == 0 && res.a1 == 1);
>
> return res.a0;
> @@ -150,7 +157,8 @@ static int call_lfa_activate(void *data)
>
> static int activate_fw_image(struct image_props *attrs)
> {
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
> int ret;
>
> /*
> @@ -159,8 +167,10 @@ static int activate_fw_image(struct image_props *attrs)
> * LFA_PRIME/ACTIVATE will need to be called again.
> * res.a1 will become 0 once the prime/activate process completes.
> */
> + args.a0 = LFA_1_0_FN_PRIME;
> + args.a1 = attrs->fw_seq_id; /* fw_seq_id under consideration */
> do {
> - arm_smccc_1_1_invoke(LFA_1_0_FN_PRIME, attrs->fw_seq_id, &res);
> + arm_smccc_1_2_invoke(&args, &res);
> if (res.a0 != LFA_SUCCESS) {
> pr_err("LFA_PRIME failed: %s\n",
> lfa_error_strings[-res.a0]);
> @@ -211,13 +221,16 @@ static ssize_t activation_pending_show(struct kobject *kobj,
> {
> struct image_props *attrs = container_of(attr, struct image_props,
> image_attrs[LFA_ATTR_ACT_PENDING]);
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
>
> /*
> * Activation pending status can change anytime thus we need to update
> * and return its current value
> */
> - arm_smccc_1_1_invoke(LFA_1_0_FN_GET_INVENTORY, attrs->fw_seq_id, &res);
> + args.a0 = LFA_1_0_FN_GET_INVENTORY;
> + args.a1 = attrs->fw_seq_id;
> + arm_smccc_1_2_invoke(&args, &res);
> if (res.a0 == LFA_SUCCESS)
> attrs->activation_pending = !!(res.a3 & BIT(1));
>
> @@ -298,9 +311,12 @@ static ssize_t cancel_store(struct kobject *kobj, struct kobj_attribute *attr,
> {
> struct image_props *attrs = container_of(attr, struct image_props,
> image_attrs[LFA_ATTR_CANCEL]);
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
>
> - arm_smccc_1_1_invoke(LFA_1_0_FN_CANCEL, attrs->fw_seq_id, &res);
> + args.a0 = LFA_1_0_FN_CANCEL;
> + args.a1 = attrs->fw_seq_id;
> + arm_smccc_1_2_invoke(&args, &res);
>
> /*
> * When firmware activation is called with "skip_cpu_rendezvous=1",
> @@ -395,14 +411,17 @@ static int create_fw_inventory(char *fw_uuid, int seq_id, u32 image_flags)
>
> static int create_fw_images_tree(void)
> {
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
> struct uuid_regs image_uuid;
> char image_id_str[40];
> int ret, num_of_components;
>
> num_of_components = get_nr_lfa_components();
> + args.a0 = LFA_1_0_FN_GET_INVENTORY;
> for (int i = 0; i < num_of_components; i++) {
> - arm_smccc_1_1_invoke(LFA_1_0_FN_GET_INVENTORY, i, &res);
> + args.a1 = i; /* fw_seq_id under consideration */
> + arm_smccc_1_2_invoke(&args, &res);
> if (res.a0 == LFA_SUCCESS) {
> image_uuid.uuid_lo = res.a1;
> image_uuid.uuid_hi = res.a2;
> @@ -420,10 +439,23 @@ static int create_fw_images_tree(void)
>
> static int __init lfa_init(void)
> {
> - struct arm_smccc_res res = { 0 };
> + struct arm_smccc_1_2_regs args = { 0 };
> + struct arm_smccc_1_2_regs res = { 0 };
> int err;
>
> - arm_smccc_1_1_invoke(LFA_1_0_FN_GET_VERSION, &res);
> + /* LFA requires SMCCC version >= 1.2 */
> + if (arm_smccc_get_version() < ARM_SMCCC_VERSION_1_2) {
> + pr_err("Not supported with SMCCC version %u", arm_smccc_get_version());
> + return -ENODEV;
> + }
> +
> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE) {
> + pr_err("Invalid SMCCC conduit");
> + return -ENODEV;
> + }
> +
> + args.a0 = LFA_1_0_FN_GET_VERSION;
> + arm_smccc_1_2_invoke(&args, &res);
> if (res.a0 == -LFA_NOT_SUPPORTED) {
> pr_err("Arm Live Firmware activation(LFA): no firmware agent found\n");
> return -ENODEV;
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