irqchip/qcom-mpm: Support passing a slice of SRAM as reg space

The MPM hardware is accessible from the ARM CPUs through a shared memory
region (RPM MSG RAM) which is 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
requires 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 a property

Go with the third option and add a way to map a region passed through the
"qcom,rpm-msg-ram" property as register space for the MPM interrupt
controller.

The current way of using 'reg' is preserved for backwards compatibility
reasons.

[ tglx: Massaged changelog ]

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Link: https://lore.kernel.org/r/20230328-topic-msgram_mpm-v7-2-6ee2bfeaac2c@linaro.org

diff --git a/drivers/irqchip/irq-qcom-mpm.c b/drivers/irqchip/irq-qcom-mpm.c
index 7124565234a5863e23ccbf6be390213fa8e42069..cda5838d2232dc1971369b4c6e872d004263b8de 100644 (file)
--- 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_platform.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 +377,26 @@ 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);
+               if (ret) {
+                       of_node_put(msgram_np);
+                       return ret;
+               }
+
+               /* Don't use devm_ioremap_resource, as we're accessing a shared region. */
+               priv->base = devm_ioremap(dev, res.start, resource_size(&res));
+               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);