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nvmem: imx: scu: support write
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The fuse programming from non-secure world is blocked, so we could
only use Arm Trusted Firmware SIP call to let ATF program fuse.

Because there is ECC region that could only be programmed once,
so add a heler in_ecc to check the ecc region.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20191029114240.14905-5-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Peng Fan authored and Greg Kroah-Hartman committed Nov 5, 2019
1 parent f8017bf commit 885ce72
Showing 1 changed file with 72 additions and 1 deletion.
73 changes: 72 additions & 1 deletion drivers/nvmem/imx-ocotp-scu.c
Original file line number Diff line number Diff line change
Expand Up @@ -7,13 +7,17 @@
* Peng Fan <peng.fan@nxp.com>
*/

#include <linux/arm-smccc.h>
#include <linux/firmware/imx/sci.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define IMX_SIP_OTP 0xC200000A
#define IMX_SIP_OTP_WRITE 0x2

enum ocotp_devtype {
IMX8QXP,
IMX8QM,
Expand Down Expand Up @@ -46,6 +50,8 @@ struct imx_sc_msg_misc_fuse_read {
u32 word;
} __packed;

static DEFINE_MUTEX(scu_ocotp_mutex);

static struct ocotp_devtype_data imx8qxp_data = {
.devtype = IMX8QXP,
.nregs = 800,
Expand Down Expand Up @@ -84,6 +90,23 @@ static bool in_hole(void *context, u32 index)
return false;
}

static bool in_ecc(void *context, u32 index)
{
struct ocotp_priv *priv = context;
const struct ocotp_devtype_data *data = priv->data;
int i;

for (i = 0; i < data->num_region; i++) {
if (data->region[i].flag & ECC_REGION) {
if ((index >= data->region[i].start) &&
(index <= data->region[i].end))
return true;
}
}

return false;
}

static int imx_sc_misc_otp_fuse_read(struct imx_sc_ipc *ipc, u32 word,
u32 *val)
{
Expand Down Expand Up @@ -127,6 +150,8 @@ static int imx_scu_ocotp_read(void *context, unsigned int offset,
if (!p)
return -ENOMEM;

mutex_lock(&scu_ocotp_mutex);

buf = p;

for (i = index; i < (index + count); i++) {
Expand All @@ -137,6 +162,7 @@ static int imx_scu_ocotp_read(void *context, unsigned int offset,

ret = imx_sc_misc_otp_fuse_read(priv->nvmem_ipc, i, buf);
if (ret) {
mutex_unlock(&scu_ocotp_mutex);
kfree(p);
return ret;
}
Expand All @@ -145,18 +171,63 @@ static int imx_scu_ocotp_read(void *context, unsigned int offset,

memcpy(val, (u8 *)p + offset % 4, bytes);

mutex_unlock(&scu_ocotp_mutex);

kfree(p);

return 0;
}

static int imx_scu_ocotp_write(void *context, unsigned int offset,
void *val, size_t bytes)
{
struct ocotp_priv *priv = context;
struct arm_smccc_res res;
u32 *buf = val;
u32 tmp;
u32 index;
int ret;

/* allow only writing one complete OTP word at a time */
if ((bytes != 4) || (offset % 4))
return -EINVAL;

index = offset >> 2;

if (in_hole(context, index))
return -EINVAL;

if (in_ecc(context, index)) {
pr_warn("ECC region, only program once\n");
mutex_lock(&scu_ocotp_mutex);
ret = imx_sc_misc_otp_fuse_read(priv->nvmem_ipc, index, &tmp);
mutex_unlock(&scu_ocotp_mutex);
if (ret)
return ret;
if (tmp) {
pr_warn("ECC region, already has value: %x\n", tmp);
return -EIO;
}
}

mutex_lock(&scu_ocotp_mutex);

arm_smccc_smc(IMX_SIP_OTP, IMX_SIP_OTP_WRITE, index, *buf,
0, 0, 0, 0, &res);

mutex_unlock(&scu_ocotp_mutex);

return res.a0;
}

static struct nvmem_config imx_scu_ocotp_nvmem_config = {
.name = "imx-scu-ocotp",
.read_only = true,
.read_only = false,
.word_size = 4,
.stride = 1,
.owner = THIS_MODULE,
.reg_read = imx_scu_ocotp_read,
.reg_write = imx_scu_ocotp_write,
};

static const struct of_device_id imx_scu_ocotp_dt_ids[] = {
Expand Down

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