firmware: qcom_scm: Fix legacy convention SCM accessors

The move to a combined driver for the QCOM SCM hardware changed the
io_writel and io_readl helpers to use non-atomic calls, despite the
commit message saying that atomic was a better option. This breaks these
helpers on hardware that uses the old legacy convention (access fails
with a -95 return code). Switch back to using the atomic calls.

Observed as a failure routing GPIO interrupts to the Apps processor on
an IPQ8064; fix is confirmed as correctly allowing the interrupts to be
routed and observed.
Reviewed-by: Elliot Berman <eberman@codeaurora.org>
Fixes: 57d3b816 ("firmware: qcom_scm: Remove thin wrappers")
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan McDowell <noodles@earth.li>
Link: https://lore.kernel.org/r/20200704172334.GA759@earth.liSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/firmware/qcom_scm.c

@@ -391,7 +391,7 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
 
 	desc.args[1] = enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0;
 
-	return qcom_scm_call(__scm->dev, &desc, NULL);
+	return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
 }
 
 static void qcom_scm_set_download_mode(bool enable)
@@ -650,7 +650,7 @@ int qcom_scm_io_readl(phys_addr_t addr, unsigned int *val)
 	int ret;
 
 
-	ret = qcom_scm_call(__scm->dev, &desc, &res);
+	ret = qcom_scm_call_atomic(__scm->dev, &desc, &res);
 	if (ret >= 0)
 		*val = res.result[0];
 
@@ -669,8 +669,7 @@ int qcom_scm_io_writel(phys_addr_t addr, unsigned int val)
 		.owner = ARM_SMCCC_OWNER_SIP,
 	};
 
-
-	return qcom_scm_call(__scm->dev, &desc, NULL);
+	return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
 }
 EXPORT_SYMBOL(qcom_scm_io_writel);