Merge "qcom: scm: Implement a retry mechanism" (ca19e365) · Commits · e / devices / android_kernel_sony_msm8994

drivers/soc/qcom/scm.c

+39 −1

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		#include <linux/errno.h>
		#include <linux/err.h>
		#include <linux/init.h>
		#include <linux/delay.h>

		#include <asm/cacheflush.h>
		#include <asm/compiler.h>
		@@ -29,9 +30,13 @@
		#define SCM_EINVAL_ARG -2
		#define SCM_ERROR -1
		#define SCM_INTERRUPTED 1
		#define SCM_EBUSY -55

		static DEFINE_MUTEX(scm_lock);

		#define SCM_EBUSY_WAIT_MS 30
		#define SCM_EBUSY_MAX_RETRY 20

		#define SCM_BUF_LEN(__cmd_size, __resp_size) \
		(sizeof(struct scm_command) + sizeof(struct scm_response) + \
		__cmd_size + __resp_size)
		@@ -139,6 +144,7 @@ static inline void scm_get_response_buffer(const struct scm_response rsp)

		static int scm_remap_error(int err)
		{
		if (err != SCM_EBUSY)
		pr_err("scm_call failed with error code %d\n", err);
		switch (err) {
		case SCM_ERROR:
		@@ -150,6 +156,8 @@ static int scm_remap_error(int err)
		return -EOPNOTSUPP;
		case SCM_ENOMEM:
		return -ENOMEM;
		case SCM_EBUSY:
		return SCM_EBUSY;
		}
		return -EINVAL;
		}
		@@ -281,6 +289,33 @@ static int scm_call_common(u32 svc_id, u32 cmd_id, const void *cmd_buf,
		return ret;
		}

		/*
		* Sometimes the secure world may be busy waiting for a particular resource.
		* In those situations, it is expected that the secure world returns a special
		* error code (SCM_EBUSY). Retry any scm_call that fails with this error code,
		* but with a timeout in place. Also, don't move this into scm_call_common,
		* since we want the first attempt to be the "fastpath".
		*/
		static int _scm_call_retry(u32 svc_id, u32 cmd_id, const void *cmd_buf,
		size_t cmd_len, void *resp_buf, size_t resp_len,
		struct scm_command *cmd,
		size_t len)
		{
		int ret, retry_count = 0;

		do {
		ret = scm_call_common(svc_id, cmd_id, cmd_buf, cmd_len,
		resp_buf, resp_len, cmd, len);
		if (ret == SCM_EBUSY)
		msleep(SCM_EBUSY_WAIT_MS);
		} while (ret == SCM_EBUSY && (retry_count++ < SCM_EBUSY_MAX_RETRY));

		if (ret == SCM_EBUSY)
		pr_err("scm: secure world busy (rc = SCM_EBUSY)\n");

		return ret;
		}

		/**
		* scm_call_noalloc - Send an SCM command
		*
		@@ -344,6 +379,9 @@ int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,

		ret = scm_call_common(svc_id, cmd_id, cmd_buf, cmd_len, resp_buf,
		resp_len, cmd, len);
		if (unlikely(ret == SCM_EBUSY))
		ret = _scm_call_retry(svc_id, cmd_id, cmd_buf, cmd_len,
		resp_buf, resp_len, cmd, PAGE_ALIGN(len));
		kfree(cmd);
		return ret;
		}