diff options
Diffstat (limited to 'drivers/nvmem/imx-ocotp.c')
| -rw-r--r-- | drivers/nvmem/imx-ocotp.c | 52 |
1 files changed, 44 insertions, 8 deletions
diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c index bd016b928589..42d4451e7d67 100644 --- a/drivers/nvmem/imx-ocotp.c +++ b/drivers/nvmem/imx-ocotp.c @@ -39,12 +39,14 @@ #define IMX_OCOTP_ADDR_DATA2 0x0040 #define IMX_OCOTP_ADDR_DATA3 0x0050 -#define IMX_OCOTP_BM_CTRL_ADDR 0x0000007F +#define IMX_OCOTP_BM_CTRL_ADDR 0x000000FF #define IMX_OCOTP_BM_CTRL_BUSY 0x00000100 #define IMX_OCOTP_BM_CTRL_ERROR 0x00000200 #define IMX_OCOTP_BM_CTRL_REL_SHADOWS 0x00000400 -#define DEF_RELAX 20 /* > 16.5ns */ +#define TIMING_STROBE_PROG_US 10 /* Min time to blow a fuse */ +#define TIMING_STROBE_READ_NS 37 /* Min time before read */ +#define TIMING_RELAX_NS 17 #define DEF_FSOURCE 1001 /* > 1000 ns */ #define DEF_STROBE_PROG 10000 /* IPG clocks */ #define IMX_OCOTP_WR_UNLOCK 0x3E770000 @@ -176,14 +178,41 @@ static void imx_ocotp_set_imx6_timing(struct ocotp_priv *priv) * fields with timing values to match the current frequency of the * ipg_clk. OTP writes will work at maximum bus frequencies as long * as the HW_OCOTP_TIMING parameters are set correctly. + * + * Note: there are minimum timings required to ensure an OTP fuse burns + * correctly that are independent of the ipg_clk. Those values are not + * formally documented anywhere however, working from the minimum + * timings given in u-boot we can say: + * + * - Minimum STROBE_PROG time is 10 microseconds. Intuitively 10 + * microseconds feels about right as representative of a minimum time + * to physically burn out a fuse. + * + * - Minimum STROBE_READ i.e. the time to wait post OTP fuse burn before + * performing another read is 37 nanoseconds + * + * - Minimum RELAX timing is 17 nanoseconds. This final RELAX minimum + * timing is not entirely clear the documentation says "This + * count value specifies the time to add to all default timing + * parameters other than the Tpgm and Trd. It is given in number + * of ipg_clk periods." where Tpgm and Trd refer to STROBE_PROG + * and STROBE_READ respectively. What the other timing parameters + * are though, is not specified. Experience shows a zero RELAX + * value will mess up a re-load of the shadow registers post OTP + * burn. */ clk_rate = clk_get_rate(priv->clk); - relax = clk_rate / (1000000000 / DEF_RELAX) - 1; - strobe_prog = clk_rate / (1000000000 / 10000) + 2 * (DEF_RELAX + 1) - 1; - strobe_read = clk_rate / (1000000000 / 40) + 2 * (DEF_RELAX + 1) - 1; + relax = DIV_ROUND_UP(clk_rate * TIMING_RELAX_NS, 1000000000) - 1; + strobe_read = DIV_ROUND_UP(clk_rate * TIMING_STROBE_READ_NS, + 1000000000); + strobe_read += 2 * (relax + 1) - 1; + strobe_prog = DIV_ROUND_CLOSEST(clk_rate * TIMING_STROBE_PROG_US, + 1000000); + strobe_prog += 2 * (relax + 1) - 1; - timing = strobe_prog & 0x00000FFF; + timing = readl(priv->base + IMX_OCOTP_ADDR_TIMING) & 0x0FC00000; + timing |= strobe_prog & 0x00000FFF; timing |= (relax << 12) & 0x0000F000; timing |= (strobe_read << 16) & 0x003F0000; @@ -440,8 +469,14 @@ static const struct ocotp_params imx7ulp_params = { static const struct ocotp_params imx8mq_params = { .nregs = 256, - .bank_address_words = 4, - .set_timing = imx_ocotp_set_imx7_timing, + .bank_address_words = 0, + .set_timing = imx_ocotp_set_imx6_timing, +}; + +static const struct ocotp_params imx8mm_params = { + .nregs = 256, + .bank_address_words = 0, + .set_timing = imx_ocotp_set_imx6_timing, }; static const struct of_device_id imx_ocotp_dt_ids[] = { @@ -454,6 +489,7 @@ static const struct of_device_id imx_ocotp_dt_ids[] = { { .compatible = "fsl,imx6sll-ocotp", .data = &imx6sll_params }, { .compatible = "fsl,imx7ulp-ocotp", .data = &imx7ulp_params }, { .compatible = "fsl,imx8mq-ocotp", .data = &imx8mq_params }, + { .compatible = "fsl,imx8mm-ocotp", .data = &imx8mm_params }, { }, }; MODULE_DEVICE_TABLE(of, imx_ocotp_dt_ids); |