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

Konrad Dybcio
2023-03-28T10:03:41Z

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));
+ 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