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Subject[PATCH 2/3] firmware: qcom_scm: Cleanup code in qcom_scm_assign_mem()
Date
There are some questionable coding styles in this function. It looks
quite odd to deref a pointer with array indexing that only uses the
first element. Also, destroying an input/output variable halfway through
the function and then overwriting it on success is not clear. It's
better to use a local variable and the kernel macros to step through
each bit set in a bitmask and clearly show where outputs are set.

Cc: Ian Jackson <ian.jackson@citrix.com>
Cc: Julien Grall <julien.grall@arm.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Avaneesh Kumar Dwivedi <akdwived@codeaurora.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
drivers/firmware/qcom_scm.c | 34 ++++++++++++++++------------------
include/linux/qcom_scm.h | 9 +++++----
2 files changed, 21 insertions(+), 22 deletions(-)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 0c63495cf269..153f13f72bac 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -443,7 +443,8 @@ EXPORT_SYMBOL(qcom_scm_set_remote_state);
*/
int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
unsigned int *srcvm,
- struct qcom_scm_vmperm *newvm, int dest_cnt)
+ const struct qcom_scm_vmperm *newvm,
+ unsigned int dest_cnt)
{
struct qcom_scm_current_perm_info *destvm;
struct qcom_scm_mem_map_info *mem_to_map;
@@ -458,11 +459,10 @@ int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
int next_vm;
__le32 *src;
void *ptr;
- int ret;
- int len;
- int i;
+ int ret, i, b;
+ unsigned long srcvm_bits = *srcvm;

- src_sz = hweight_long(*srcvm) * sizeof(*src);
+ src_sz = hweight_long(srcvm_bits) * sizeof(*src);
mem_to_map_sz = sizeof(*mem_to_map);
dest_sz = dest_cnt * sizeof(*destvm);
ptr_sz = ALIGN(src_sz, SZ_64) + ALIGN(mem_to_map_sz, SZ_64) +
@@ -475,28 +475,26 @@ int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,

/* Fill source vmid detail */
src = ptr;
- len = hweight_long(*srcvm);
- for (i = 0; i < len; i++) {
- src[i] = cpu_to_le32(ffs(*srcvm) - 1);
- *srcvm ^= 1 << (ffs(*srcvm) - 1);
- }
+ i = 0;
+ for_each_set_bit(b, &srcvm_bits, sizeof(srcvm_bits))
+ src[i++] = cpu_to_le32(b);

/* Fill details of mem buff to map */
mem_to_map = ptr + ALIGN(src_sz, SZ_64);
mem_to_map_phys = ptr_phys + ALIGN(src_sz, SZ_64);
- mem_to_map[0].mem_addr = cpu_to_le64(mem_addr);
- mem_to_map[0].mem_size = cpu_to_le64(mem_sz);
+ mem_to_map->mem_addr = cpu_to_le64(mem_addr);
+ mem_to_map->mem_size = cpu_to_le64(mem_sz);

next_vm = 0;
/* Fill details of next vmid detail */
destvm = ptr + ALIGN(mem_to_map_sz, SZ_64) + ALIGN(src_sz, SZ_64);
dest_phys = ptr_phys + ALIGN(mem_to_map_sz, SZ_64) + ALIGN(src_sz, SZ_64);
- for (i = 0; i < dest_cnt; i++) {
- destvm[i].vmid = cpu_to_le32(newvm[i].vmid);
- destvm[i].perm = cpu_to_le32(newvm[i].perm);
- destvm[i].ctx = 0;
- destvm[i].ctx_size = 0;
- next_vm |= BIT(newvm[i].vmid);
+ for (i = 0; i < dest_cnt; i++, destvm++, newvm++) {
+ destvm->vmid = cpu_to_le32(newvm->vmid);
+ destvm->perm = cpu_to_le32(newvm->perm);
+ destvm->ctx = 0;
+ destvm->ctx_size = 0;
+ next_vm |= BIT(newvm->vmid);
}

ret = __qcom_scm_assign_mem(__scm->dev, mem_to_map_phys, mem_to_map_sz,
diff --git a/include/linux/qcom_scm.h b/include/linux/qcom_scm.h
index d0aecc04c54b..1d406403c843 100644
--- a/include/linux/qcom_scm.h
+++ b/include/linux/qcom_scm.h
@@ -57,8 +57,9 @@ extern int qcom_scm_pas_mem_setup(u32 peripheral, phys_addr_t addr,
extern int qcom_scm_pas_auth_and_reset(u32 peripheral);
extern int qcom_scm_pas_shutdown(u32 peripheral);
extern int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
- unsigned int *src, struct qcom_scm_vmperm *newvm,
- int dest_cnt);
+ unsigned int *src,
+ const struct qcom_scm_vmperm *newvm,
+ unsigned int dest_cnt);
extern void qcom_scm_cpu_power_down(u32 flags);
extern u32 qcom_scm_get_version(void);
extern int qcom_scm_set_remote_state(u32 state, u32 id);
@@ -95,8 +96,8 @@ qcom_scm_pas_auth_and_reset(u32 peripheral) { return -ENODEV; }
static inline int qcom_scm_pas_shutdown(u32 peripheral) { return -ENODEV; }
static inline int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
unsigned int *src,
- struct qcom_scm_vmperm *newvm,
- int dest_cnt) { return -ENODEV; }
+ const struct qcom_scm_vmperm *newvm,
+ unsigned int dest_cnt) { return -ENODEV; }
static inline void qcom_scm_cpu_power_down(u32 flags) {}
static inline u32 qcom_scm_get_version(void) { return 0; }
static inline u32
--
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