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Subject[PATCH] firmware: gsmi: Drop the use of dma_pool_* API functions
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GSMI driver uses dma_pool_* API functions for buffer allocation
because it requires that the SMI buffers are allocated within 32-bit
physical address space. However, this does not work well with IOMMU
since there is no real device and hence no domain associated with the
device.

Since this is not a real device, it does not require any device
address(IOVA) for the buffer allocations. The only requirement is to
ensure that the physical address allocated to the buffer is within
32-bit physical address space. This change allocates a page using
`get_zeroed_page()` and passes in GFP_DMA32 flag to ensure that the
page allocation is done in the DMA32 zone. All the buffer allocation
requests for gsmi_buf are then satisfed using this pre-allocated page
for the device.

In addition to that, all the code for managing the dma_pool for GSMI
platform device is dropped.

Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Prashant Malani <pmalani@chromium.org>
---
drivers/firmware/google/gsmi.c | 100 +++++++++++++++++++++++----------
1 file changed, 71 insertions(+), 29 deletions(-)

diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c
index 7d9367b22010..054c47346900 100644
--- a/drivers/firmware/google/gsmi.c
+++ b/drivers/firmware/google/gsmi.c
@@ -17,7 +17,6 @@
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/dma-mapping.h>
-#include <linux/dmapool.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
@@ -46,7 +45,6 @@
#define DRIVER_VERSION "1.0"
#define GSMI_GUID_SIZE 16
#define GSMI_BUF_SIZE 1024
-#define GSMI_BUF_ALIGN sizeof(u64)
#define GSMI_CALLBACK 0xef

/* SMI return codes */
@@ -85,10 +83,15 @@
struct gsmi_buf {
u8 *start; /* start of buffer */
size_t length; /* length of buffer */
- dma_addr_t handle; /* dma allocation handle */
u32 address; /* physical address of buffer */
};

+struct gsmi_page {
+ unsigned long base_address; /* Base address of allocated page */
+ size_t alloc_size; /* Size of allocation */
+ size_t alloc_used; /* Amount of allocation that is used */
+};
+
static struct gsmi_device {
struct platform_device *pdev; /* platform device */
struct gsmi_buf *name_buf; /* variable name buffer */
@@ -97,7 +100,7 @@ static struct gsmi_device {
spinlock_t lock; /* serialize access to SMIs */
u16 smi_cmd; /* SMI command port */
int handshake_type; /* firmware handler interlock type */
- struct dma_pool *dma_pool; /* DMA buffer pool */
+ struct gsmi_page *page_info; /* page allocated for GSMI buffers */
} gsmi_dev;

/* Packed structures for communicating with the firmware */
@@ -146,9 +149,57 @@ MODULE_PARM_DESC(spincount,
static bool s0ix_logging_enable;
module_param(s0ix_logging_enable, bool, 0600);

+static struct gsmi_page *gsmi_page_alloc(void)
+{
+ struct gsmi_page *page_info;
+
+ page_info = kzalloc(sizeof(*page_info), GFP_KERNEL);
+ if (!page_info) {
+ printk(KERN_ERR "gsmi: out of memory\n");
+ return NULL;
+ }
+
+ page_info->base_address = get_zeroed_page(GFP_KERNEL | GFP_DMA32);
+ if (!page_info->base_address) {
+ printk(KERN_ERR "gsmi: failed to allocate page for buffers\n");
+ return NULL;
+ }
+
+ /* Ensure the entire buffer is allocated within 32bit address space */
+ if (virt_to_phys((void *)(page_info->base_address + PAGE_SIZE - 1))
+ >> 32) {
+ printk(KERN_ERR "gsmi: allocation not within 32-bit physical address space\n");
+ free_page(page_info->base_address);
+ kfree(page_info);
+ return NULL;
+ }
+
+ page_info->alloc_size = PAGE_SIZE;
+
+ return page_info;
+}
+
+static unsigned long gsmi_page_allocate_buffer(void)
+{
+ struct gsmi_page *page_info = gsmi_dev.page_info;
+ unsigned long buf_offset = page_info->alloc_used;
+
+ if (buf_offset + GSMI_BUF_SIZE > page_info->alloc_size) {
+ printk(KERN_ERR "gsmi: out of space for buffer allocation\n");
+ return 0;
+ }
+
+ page_info->alloc_used = buf_offset + GSMI_BUF_SIZE;
+ return page_info->base_address + buf_offset;
+}
+
static struct gsmi_buf *gsmi_buf_alloc(void)
{
struct gsmi_buf *smibuf;
+ u8 *buf_addr = (u8 *)gsmi_page_allocate_buffer();
+
+ if (!buf_addr)
+ return NULL;

smibuf = kzalloc(sizeof(*smibuf), GFP_KERNEL);
if (!smibuf) {
@@ -156,14 +207,7 @@ static struct gsmi_buf *gsmi_buf_alloc(void)
return NULL;
}

- /* allocate buffer in 32bit address space */
- smibuf->start = dma_pool_alloc(gsmi_dev.dma_pool, GFP_KERNEL,
- &smibuf->handle);
- if (!smibuf->start) {
- printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
- kfree(smibuf);
- return NULL;
- }
+ smibuf->start = buf_addr;

/* fill in the buffer handle */
smibuf->length = GSMI_BUF_SIZE;
@@ -172,13 +216,15 @@ static struct gsmi_buf *gsmi_buf_alloc(void)
return smibuf;
}

-static void gsmi_buf_free(struct gsmi_buf *smibuf)
+static void gsmi_free_alloc(void)
{
- if (smibuf) {
- if (smibuf->start)
- dma_pool_free(gsmi_dev.dma_pool, smibuf->start,
- smibuf->handle);
- kfree(smibuf);
+ kfree(gsmi_dev.param_buf);
+ kfree(gsmi_dev.data_buf);
+ kfree(gsmi_dev.name_buf);
+
+ if (gsmi_dev.page_info) {
+ free_page(gsmi_dev.page_info->base_address);
+ kfree(gsmi_dev.page_info);
}
}

@@ -914,10 +960,12 @@ static __init int gsmi_init(void)
spin_lock_init(&gsmi_dev.lock);

ret = -ENOMEM;
- gsmi_dev.dma_pool = dma_pool_create("gsmi", &gsmi_dev.pdev->dev,
- GSMI_BUF_SIZE, GSMI_BUF_ALIGN, 0);
- if (!gsmi_dev.dma_pool)
+
+ gsmi_dev.page_info = gsmi_page_alloc();
+ if (!gsmi_dev.page_info) {
+ printk(KERN_ERR "gsmi: failed to allocate page\n");
goto out_err;
+ }

/*
* pre-allocate buffers because sometimes we are called when
@@ -1029,10 +1077,7 @@ static __init int gsmi_init(void)
sysfs_remove_bin_file(gsmi_kobj, &eventlog_bin_attr);
out_err:
kobject_put(gsmi_kobj);
- gsmi_buf_free(gsmi_dev.param_buf);
- gsmi_buf_free(gsmi_dev.data_buf);
- gsmi_buf_free(gsmi_dev.name_buf);
- dma_pool_destroy(gsmi_dev.dma_pool);
+ gsmi_free_alloc();
platform_device_unregister(gsmi_dev.pdev);
pr_info("gsmi: failed to load: %d\n", ret);
#ifdef CONFIG_PM
@@ -1054,10 +1099,7 @@ static void __exit gsmi_exit(void)
sysfs_remove_files(gsmi_kobj, gsmi_attrs);
sysfs_remove_bin_file(gsmi_kobj, &eventlog_bin_attr);
kobject_put(gsmi_kobj);
- gsmi_buf_free(gsmi_dev.param_buf);
- gsmi_buf_free(gsmi_dev.data_buf);
- gsmi_buf_free(gsmi_dev.name_buf);
- dma_pool_destroy(gsmi_dev.dma_pool);
+ gsmi_free_alloc();
platform_device_unregister(gsmi_dev.pdev);
#ifdef CONFIG_PM
platform_driver_unregister(&gsmi_driver_info);
--
2.29.0.rc1.297.gfa9743e501-goog
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