Re: [PATCH 2/2] irqchip: irq-qcom-mpm: Support passing a slice of SRAM as reg space

Shawn Guo
2023-03-29T03:50:13Z

On Tue, Mar 28, 2023 at 12:02:53PM +0200, Konrad Dybcio wrote:
> The MPM hardware is accessible to us from the ARM CPUs through a shared
> memory region (RPM MSG RAM) that's also concurrently accessed by other
> kinds of cores on the system (like modem, ADSP etc.). Modeling this
> relation in a (somewhat) sane manner in the device tree basically
> requires us to either present the MPM as a child of said memory region
> (which makes little sense, as a mapped memory carveout is not a bus),
> define nodes which bleed their register spaces into one another, or
> passing their slice of the MSG RAM through some kind of a property.
>
> Go with the third option and add a way to map a region passed through
> the "qcom,rpm-msg-ram" property as our register space.
>
> The current way of using 'reg' is preserved for ABI reasons.
>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> ---
> drivers/irqchip/irq-qcom-mpm.c | 30 +++++++++++++++++++++++++-----
> 1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/irqchip/irq-qcom-mpm.c b/drivers/irqchip/irq-qcom-mpm.c
> index d30614661eea..6fe59f4deef4 100644
> --- a/drivers/irqchip/irq-qcom-mpm.c
> +++ b/drivers/irqchip/irq-qcom-mpm.c
> @@ -14,6 +14,7 @@
> #include <linux/mailbox_client.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_address.h>
> #include <linux/of_device.h>
> #include <linux/platform_device.h>
> #include <linux/pm_domain.h>
> @@ -322,8 +323,10 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
> struct device *dev = &pdev->dev;
> struct irq_domain *parent_domain;
> struct generic_pm_domain *genpd;
> + struct device_node *msgram_np;
> struct qcom_mpm_priv *priv;
> unsigned int pin_cnt;
> + struct resource res;
> int i, irq;
> int ret;
>
> @@ -374,9 +377,21 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
>
> raw_spin_lock_init(&priv->lock);
>
> - priv->base = devm_platform_ioremap_resource(pdev, 0);
> - if (IS_ERR(priv->base))
> - return PTR_ERR(priv->base);
> + /* If we have a handle to an RPM message ram partition, use it. */
> + msgram_np = of_parse_phandle(np, "qcom,rpm-msg-ram", 0);
> + if (msgram_np) {
> + ret = of_address_to_resource(msgram_np, 0, &res);
> + /* Don't use devm_ioremap_resource, as we're accessing a shared region. */
> + priv->base = ioremap(res.start, resource_size(&res));

Are you suggesting that other cores/drivers will also need to access
the mpm slice below?

apss_mpm: sram@1b8 {
reg = <0x1b8 0x48>;
};

Shawn

> + of_node_put(msgram_np);
> + if (IS_ERR(priv->base))
> + return PTR_ERR(priv->base);
> + } else {
> + /* Otherwise, fall back to simple MMIO. */
> + priv->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(priv->base))
> + return PTR_ERR(priv->base);
> + }
>
> for (i = 0; i < priv->reg_stride; i++) {
> qcom_mpm_write(priv, MPM_REG_ENABLE, i, 0);
> @@ -387,8 +402,10 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
> }
>
> irq = platform_get_irq(pdev, 0);
> - if (irq < 0)
> - return irq;
> + if (irq < 0) {
> + ret = irq;
> + goto unmap_base;
> + }
>
> genpd = &priv->genpd;
> genpd->flags = GENPD_FLAG_IRQ_SAFE;
> @@ -451,6 +468,9 @@ static int qcom_mpm_init(struct device_node *np, struct device_node *parent)
> mbox_free_channel(priv->mbox_chan);
> remove_genpd:
> pm_genpd_remove(genpd);
> +unmap_base:
> + if (res.start)
> + iounmap(priv->base);
> return ret;
> }
>
>
> --
> 2.40.0
>