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misc: sram: add Atmel securam support 

The Atmel secure SRAM is connected to a security module and may be erased
automatically under certain conditions. For that reason, it is necessary to
wait for the security module to flag that SRAM accesses are allowed before
accessing it.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexandre Belloni 2016-09-22 00:09:38 +02:00
parent 15adffadc5
commit 2ae2e28852
1 changed files with 35 additions and 7 deletions
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42
drivers/misc/sram.c
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@ -19,12 +19,17 @@
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/genalloc.h>
#include <linux/io.h>
#include <linux/list_sort.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/mfd/syscon.h>
#include <soc/at91/atmel-secumod.h>
#define SRAM_GRANULARITY 32
@ -334,12 +339,35 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
return ret;
}
static int atmel_securam_wait(void)
{
struct regmap *regmap;
u32 val;
regmap = syscon_regmap_lookup_by_compatible("atmel,sama5d2-secumod");
if (IS_ERR(regmap))
return -ENODEV;
return regmap_read_poll_timeout(regmap, AT91_SECUMOD_RAMRDY, val,
val & AT91_SECUMOD_RAMRDY_READY,
10000, 500000);
}
#ifdef CONFIG_OF
static const struct of_device_id sram_dt_ids[] = {
{ .compatible = "mmio-sram" },
{ .compatible = "atmel,sama5d2-securam", .data = atmel_securam_wait },
{}
};
#endif
static int sram_probe(struct platform_device *pdev)
{
struct sram_dev *sram;
struct resource *res;
size_t size;
int ret;
int (*init_func)(void);
sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
if (!sram)
@ -384,6 +412,13 @@ static int sram_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, sram);
init_func = of_device_get_match_data(&pdev->dev);
if (init_func) {
ret = init_func();
if (ret)
return ret;
}
dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n",
gen_pool_size(sram->pool) / 1024, sram->virt_base);
@ -405,13 +440,6 @@ static int sram_remove(struct platform_device *pdev)
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id sram_dt_ids[] = {
{ .compatible = "mmio-sram" },
{}
};
#endif
static struct platform_driver sram_driver = {
.driver = {
.name = "sram",