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Message-ID: <3f5f42e5-265f-40f1-af38-7057622270d2@quicinc.com>
Date: Fri, 27 Oct 2023 16:44:53 -0700
From: Jeff Johnson <quic_jjohnson@...cinc.com>
To: Guru Das Srinagesh <quic_gurus@...cinc.com>,
Andy Gross <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>
CC: <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<kernel@...cinc.com>
Subject: Re: [PATCH] firmware: qcom-scm: Support multiple waitq contexts
On 10/27/2023 3:37 PM, Guru Das Srinagesh wrote:
> Currently, only a single waitqueue context is supported (zero). Firmware
which firmware?
> now supports multiple waitqueue contexts, so add support to dynamically
> create and support as many unique waitqueue contexts as firmware returns
> to the driver.
>
> This is done by using the idr framework to create a hash table for
why idr?
Per https://docs.kernel.org/core-api/idr.html
"The IDR interface is deprecated; please use the XArray instead."
> associating a unique wq_ctx with a struct completion variable for easy
> lookup.
>
> Signed-off-by: Guru Das Srinagesh <quic_gurus@...cinc.com>
> ---
> This series is based on the tip of linux-next because a couple of SCM
> driver-related patches are still in-flight in Bjorn's tree.
> ---
> drivers/firmware/qcom/qcom_scm-smc.c | 7 ++-
> drivers/firmware/qcom/qcom_scm.c | 90 +++++++++++++++++++++++++++---------
> drivers/firmware/qcom/qcom_scm.h | 3 +-
> 3 files changed, 77 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/firmware/qcom/qcom_scm-smc.c b/drivers/firmware/qcom/qcom_scm-smc.c
> index 16cf88acfa8e..80083e3615b1 100644
> --- a/drivers/firmware/qcom/qcom_scm-smc.c
> +++ b/drivers/firmware/qcom/qcom_scm-smc.c
> @@ -103,7 +103,12 @@ static int __scm_smc_do_quirk_handle_waitq(struct device *dev, struct arm_smccc_
> wq_ctx = res->a1;
> smc_call_ctx = res->a2;
>
> - ret = qcom_scm_wait_for_wq_completion(wq_ctx);
> + if (!dev) {
> + /* Protect the dev_get_drvdata() call that follows */
> + return -EPROBE_DEFER;
> + }
> +
> + ret = qcom_scm_wait_for_wq_completion(dev_get_drvdata(dev), wq_ctx);
> if (ret)
> return ret;
>
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 520de9b5633a..70f0c35beb16 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -10,6 +10,7 @@
> #include <linux/dma-mapping.h>
> #include <linux/export.h>
> #include <linux/firmware/qcom/qcom_scm.h>
> +#include <linux/idr.h>
> #include <linux/init.h>
> #include <linux/interconnect.h>
> #include <linux/interrupt.h>
> @@ -27,13 +28,18 @@
> static bool download_mode = IS_ENABLED(CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT);
> module_param(download_mode, bool, 0);
>
> +struct qcom_scm_waitq {
> + struct idr idr;
> + spinlock_t idr_lock;
> +};
> +
> struct qcom_scm {
> struct device *dev;
> struct clk *core_clk;
> struct clk *iface_clk;
> struct clk *bus_clk;
> struct icc_path *path;
> - struct completion waitq_comp;
> + struct qcom_scm_waitq waitq;
> struct reset_controller_dev reset;
>
> /* control access to the interconnect path */
> @@ -1742,42 +1748,76 @@ bool qcom_scm_is_available(void)
> }
> EXPORT_SYMBOL_GPL(qcom_scm_is_available);
>
> -static int qcom_scm_assert_valid_wq_ctx(u32 wq_ctx)
> +static struct completion *qcom_scm_get_completion(struct qcom_scm *scm, u32 wq_ctx)
> {
> - /* FW currently only supports a single wq_ctx (zero).
> - * TODO: Update this logic to include dynamic allocation and lookup of
> - * completion structs when FW supports more wq_ctx values.
> + struct completion *wq;
> + unsigned long flags;
> + int err;
> +
> + spin_lock_irqsave(&scm->waitq.idr_lock, flags);
> + wq = idr_find(&scm->waitq.idr, wq_ctx);
> + if (wq) {
> + /*
> + * Valid struct completion *wq found corresponding to
> + * given wq_ctx. We're done here.
> + */
> + goto out;
> + }
> +
> + /*
> + * If a struct completion *wq does not exist for wq_ctx, create it. FW
> + * only uses a finite number of wq_ctx values, so we will be reaching
> + * here only a few times right at the beginning of the device's uptime
> + * and then early-exit from idr_find() above subsequently.
> */
> - if (wq_ctx != 0) {
> - dev_err(__scm->dev, "Firmware unexpectedly passed non-zero wq_ctx\n");
> - return -EINVAL;
> + wq = devm_kzalloc(scm->dev, sizeof(*wq), GFP_ATOMIC);
> + if (!wq) {
> + wq = ERR_PTR(-ENOMEM);
> + goto out;
> }
>
> - return 0;
> + init_completion(wq);
> +
> + err = idr_alloc_u32(&scm->waitq.idr, wq, &wq_ctx, wq_ctx, GFP_ATOMIC);
> + if (err < 0) {
> + /* Don't wait for driver to be unloaded to free wq */
> + devm_kfree(scm->dev, wq);
> + wq = ERR_PTR(err);
> + }
> +
> +out:
> + spin_unlock_irqrestore(&scm->waitq.idr_lock, flags);
> + return wq;
> }
>
> -int qcom_scm_wait_for_wq_completion(u32 wq_ctx)
> +int qcom_scm_wait_for_wq_completion(struct qcom_scm *scm, u32 wq_ctx)
> {
> - int ret;
> + struct completion *wq;
>
> - ret = qcom_scm_assert_valid_wq_ctx(wq_ctx);
> - if (ret)
> - return ret;
> + wq = qcom_scm_get_completion(scm, wq_ctx);
> + if (IS_ERR(wq)) {
> + pr_err("Unable to wait on invalid waitqueue for wq_ctx %d: %ld\n",
> + wq_ctx, PTR_ERR(wq));
> + return PTR_ERR(wq);
> + }
>
> - wait_for_completion(&__scm->waitq_comp);
> + wait_for_completion(wq);
>
> return 0;
> }
>
> static int qcom_scm_waitq_wakeup(struct qcom_scm *scm, unsigned int wq_ctx)
> {
> - int ret;
> + struct completion *wq;
>
> - ret = qcom_scm_assert_valid_wq_ctx(wq_ctx);
> - if (ret)
> - return ret;
> + wq = qcom_scm_get_completion(scm, wq_ctx);
> + if (IS_ERR(wq)) {
> + pr_err("Unable to wake up invalid waitqueue for wq_ctx %d: %ld\n",
> + wq_ctx, PTR_ERR(wq));
> + return PTR_ERR(wq);
> + }
>
> - complete(&__scm->waitq_comp);
> + complete(wq);
>
> return 0;
> }
> @@ -1854,10 +1894,13 @@ static int qcom_scm_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> + platform_set_drvdata(pdev, scm);
> +
> __scm = scm;
> __scm->dev = &pdev->dev;
>
> - init_completion(&__scm->waitq_comp);
> + spin_lock_init(&__scm->waitq.idr_lock);
> + idr_init(&__scm->waitq.idr);
>
> irq = platform_get_irq_optional(pdev, 0);
> if (irq < 0) {
> @@ -1905,8 +1948,13 @@ static int qcom_scm_probe(struct platform_device *pdev)
>
> static void qcom_scm_shutdown(struct platform_device *pdev)
> {
> + struct qcom_scm *scm;
> +
> + scm = platform_get_drvdata(pdev);
> +
> /* Clean shutdown, disable download mode to allow normal restart */
> qcom_scm_set_download_mode(false);
> + idr_destroy(&scm->waitq.idr);
> }
>
> static const struct of_device_id qcom_scm_dt_match[] = {
> diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
> index 4532907e8489..d54df5a2b690 100644
> --- a/drivers/firmware/qcom/qcom_scm.h
> +++ b/drivers/firmware/qcom/qcom_scm.h
> @@ -62,7 +62,8 @@ struct qcom_scm_res {
> u64 result[MAX_QCOM_SCM_RETS];
> };
>
> -int qcom_scm_wait_for_wq_completion(u32 wq_ctx);
> +struct qcom_scm;
> +int qcom_scm_wait_for_wq_completion(struct qcom_scm *scm, u32 wq_ctx);
> int scm_get_wq_ctx(u32 *wq_ctx, u32 *flags, u32 *more_pending);
>
> #define SCM_SMC_FNID(s, c) ((((s) & 0xFF) << 8) | ((c) & 0xFF))
>
> ---
> base-commit: 2ef7141596eed0b4b45ef18b3626f428a6b0a822
> change-id: 20231027-multi-wqs-8b87fc0d3b53
>
> Best regards,
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