firmware: qcom: scm: enable the TZ mem allocator

Select the TrustZone memory allocator in Kconfig and create a pool of
memory shareable with the TrustZone when probing the SCM driver.

This will allow a gradual conversion of all relevant SCM calls to using
the dedicated allocator.

The policy used for the pool is "on-demand" and the initial size is 0
as - depending on the config - it's possible that no SCM calls needing
to allocate memory will be called. The sizes of possible allocations also
vary substiantially further warranting the "on-demand" approach.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
Tested-by: Deepti Jaggi <quic_djaggi@quicinc.com> #sa8775p-ride
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Link: https://lore.kernel.org/r/20240527-shm-bridge-v10-3-ce7afaa58d3a@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/firmware/qcom/Kconfig

@@ -7,6 +7,7 @@
 menu "Qualcomm firmware drivers"
 
 config QCOM_SCM
+	select QCOM_TZMEM
 	tristate
 
 config QCOM_TZMEM

drivers/firmware/qcom/qcom_scm.c

@@ -10,8 +10,10 @@
 #include <linux/completion.h>
 #include <linux/cpumask.h>
 #include <linux/dma-mapping.h>
+#include <linux/err.h>
 #include <linux/export.h>
 #include <linux/firmware/qcom/qcom_scm.h>
+#include <linux/firmware/qcom/qcom_tzmem.h>
 #include <linux/init.h>
 #include <linux/interconnect.h>
 #include <linux/interrupt.h>
@@ -22,9 +24,11 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/reset-controller.h>
+#include <linux/sizes.h>
 #include <linux/types.h>
 
 #include "qcom_scm.h"
+#include "qcom_tzmem.h"
 
 static bool download_mode = IS_ENABLED(CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT);
 module_param(download_mode, bool, 0);
@@ -43,6 +47,8 @@ struct qcom_scm {
 	int scm_vote_count;
 
 	u64 dload_mode_addr;
+
+	struct qcom_tzmem_pool *mempool;
 };
 
 struct qcom_scm_current_perm_info {
@@ -1824,6 +1830,7 @@ static irqreturn_t qcom_scm_irq_handler(int irq, void *data)
 
 static int qcom_scm_probe(struct platform_device *pdev)
 {
+	struct qcom_tzmem_pool_config pool_config;
 	struct qcom_scm *scm;
 	int irq, ret;
 
@@ -1899,6 +1906,21 @@ static int qcom_scm_probe(struct platform_device *pdev)
 	if (of_property_read_bool(pdev->dev.of_node, "qcom,sdi-enabled"))
 		qcom_scm_disable_sdi();
 
+	ret = qcom_tzmem_enable(__scm->dev);
+	if (ret)
+		return dev_err_probe(__scm->dev, ret,
+				     "Failed to enable the TrustZone memory allocator\n");
+
+	memset(&pool_config, 0, sizeof(pool_config));
+	pool_config.initial_size = 0;
+	pool_config.policy = QCOM_TZMEM_POLICY_ON_DEMAND;
+	pool_config.max_size = SZ_256K;
+
+	__scm->mempool = devm_qcom_tzmem_pool_new(__scm->dev, &pool_config);
+	if (IS_ERR(__scm->mempool))
+		return dev_err_probe(__scm->dev, PTR_ERR(__scm->mempool),
+				     "Failed to create the SCM memory pool\n");
+
 	/*
 	 * Initialize the QSEECOM interface.
 	 *