From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bGPBT-0005is-I0 for barebox@lists.infradead.org; Fri, 24 Jun 2016 11:22:07 +0000 From: Sascha Hauer Date: Fri, 24 Jun 2016 13:21:35 +0200 Message-Id: <1466767295-25040-2-git-send-email-s.hauer@pengutronix.de> In-Reply-To: <1466767295-25040-1-git-send-email-s.hauer@pengutronix.de> References: <1466767295-25040-1-git-send-email-s.hauer@pengutronix.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH 2/2] mtd: nand_mxs: Setup timing To: Barebox List So far we relied on the default timing values which are rather slow. This patch adds the timing setup functions from the kernel. Tested on i.MX6 with a AMD/Spansion S34ML08G2 and a Micron MT29F32G08ABAAAWP. Signed-off-by: Sascha Hauer --- drivers/mtd/nand/nand_mxs.c | 812 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 808 insertions(+), 4 deletions(-) diff --git a/drivers/mtd/nand/nand_mxs.c b/drivers/mtd/nand/nand_mxs.c index fd4e209..01aa063 100644 --- a/drivers/mtd/nand/nand_mxs.c +++ b/drivers/mtd/nand/nand_mxs.c @@ -67,16 +67,16 @@ #define GPMI_CTRL0_XFER_COUNT_OFFSET 0 #define GPMI_CTRL1 0x00000060 +#define GPMI_CTRL1_SET 0x00000064 +#define GPMI_CTRL1_CLR 0x00000068 #define GPMI_CTRL1_DECOUPLE_CS (1 << 24) -#define GPMI_CTRL1_WRN_DLY_SEL_MASK (0x3 << 22) -#define GPMI_CTRL1_WRN_DLY_SEL_OFFSET 22 +#define GPMI_CTRL1_WRN_DLY(d) (((d) & 0x3) << 22) #define GPMI_CTRL1_TIMEOUT_IRQ_EN (1 << 20) #define GPMI_CTRL1_GANGED_RDYBUSY (1 << 19) #define GPMI_CTRL1_BCH_MODE (1 << 18) #define GPMI_CTRL1_DLL_ENABLE (1 << 17) #define GPMI_CTRL1_HALF_PERIOD (1 << 16) -#define GPMI_CTRL1_RDN_DELAY_MASK (0xf << 12) -#define GPMI_CTRL1_RDN_DELAY_OFFSET 12 +#define GPMI_CTRL1_RDN_DELAY(d) (((d) & 0xf) << 12) #define GPMI_CTRL1_DMA2ECC_MODE (1 << 11) #define GPMI_CTRL1_DEV_IRQ (1 << 10) #define GPMI_CTRL1_TIMEOUT_IRQ (1 << 9) @@ -89,6 +89,20 @@ #define GPMI_CTRL1_CAMERA_MODE (1 << 1) #define GPMI_CTRL1_GPMI_MODE (1 << 0) +#define BV_GPMI_CTRL1_WRN_DLY_SEL_4_TO_8NS 0x0 +#define BV_GPMI_CTRL1_WRN_DLY_SEL_6_TO_10NS 0x1 +#define BV_GPMI_CTRL1_WRN_DLY_SEL_7_TO_12NS 0x2 +#define BV_GPMI_CTRL1_WRN_DLY_SEL_NO_DELAY 0x3 + +#define GPMI_TIMING0 0x00000070 + +#define GPMI_TIMING0_ADDRESS_SETUP(d) (((d) & 0xff) << 16) +#define GPMI_TIMING0_DATA_HOLD(d) (((d) & 0xff) << 8) +#define GPMI_TIMING0_DATA_SETUP(d) (((d) & 0xff) << 0) + +#define GPMI_TIMING1 0x00000080 +#define GPMI_TIMING1_BUSY_TIMEOUT(d) (((d) & 0xffff) << 16) + #define GPMI_ECCCTRL_HANDLE_MASK (0xffff << 16) #define GPMI_ECCCTRL_HANDLE_OFFSET 16 #define GPMI_ECCCTRL_ECC_CMD_MASK (0x3 << 13) @@ -147,7 +161,41 @@ enum gpmi_type { GPMI_IMX6, }; +/** + * struct nand_timing - Fundamental timing attributes for NAND. + * @data_setup_in_ns: The data setup time, in nanoseconds. Usually the + * maximum of tDS and tWP. A negative value + * indicates this characteristic isn't known. + * @data_hold_in_ns: The data hold time, in nanoseconds. Usually the + * maximum of tDH, tWH and tREH. A negative value + * indicates this characteristic isn't known. + * @address_setup_in_ns: The address setup time, in nanoseconds. Usually + * the maximum of tCLS, tCS and tALS. A negative + * value indicates this characteristic isn't known. + * @gpmi_sample_delay_in_ns: A GPMI-specific timing parameter. A negative value + * indicates this characteristic isn't known. + * @tREA_in_ns: tREA, in nanoseconds, from the data sheet. A + * negative value indicates this characteristic isn't + * known. + * @tRLOH_in_ns: tRLOH, in nanoseconds, from the data sheet. A + * negative value indicates this characteristic isn't + * known. + * @tRHOH_in_ns: tRHOH, in nanoseconds, from the data sheet. A + * negative value indicates this characteristic isn't + * known. + */ +struct nand_timing { + int8_t data_setup_in_ns; + int8_t data_hold_in_ns; + int8_t address_setup_in_ns; + int8_t gpmi_sample_delay_in_ns; + int8_t tREA_in_ns; + int8_t tRLOH_in_ns; + int8_t tRHOH_in_ns; +}; + struct mxs_nand_info { + struct device_d *dev; struct nand_chip nand_chip; void __iomem *io_base; void __iomem *bch_base; @@ -179,6 +227,11 @@ struct mxs_nand_info { /* DMA descriptors */ struct mxs_dma_desc **desc; uint32_t desc_index; + +#define GPMI_ASYNC_EDO_ENABLED (1 << 0) +#define GPMI_TIMING_INIT_OK (1 << 1) + unsigned flags; + struct nand_timing timing; }; struct nand_ecclayout fake_ecc_layout; @@ -1305,6 +1358,753 @@ static void mxs_nand_probe_dt(struct device_d *dev, struct mxs_nand_info *nand_i nand->bbt_options |= NAND_BBT_USE_FLASH | NAND_BBT_NO_OOB; } +/** + * struct gpmi_nfc_hardware_timing - GPMI hardware timing parameters. + * @data_setup_in_cycles: The data setup time, in cycles. + * @data_hold_in_cycles: The data hold time, in cycles. + * @address_setup_in_cycles: The address setup time, in cycles. + * @device_busy_timeout: The timeout waiting for NAND Ready/Busy, + * this value is the number of cycles multiplied + * by 4096. + * @use_half_periods: Indicates the clock is running slowly, so the + * NFC DLL should use half-periods. + * @sample_delay_factor: The sample delay factor. + * @wrn_dly_sel: The delay on the GPMI write strobe. + */ +struct gpmi_nfc_hardware_timing { + /* for GPMI_TIMING0 */ + uint8_t data_setup_in_cycles; + uint8_t data_hold_in_cycles; + uint8_t address_setup_in_cycles; + + /* for GPMI_TIMING1 */ + uint16_t device_busy_timeout; + + /* for GPMI_CTRL1 */ + bool use_half_periods; + uint8_t sample_delay_factor; + uint8_t wrn_dly_sel; +}; + +/** + * struct timing_threshod - Timing threshold + * @max_data_setup_cycles: The maximum number of data setup cycles that + * can be expressed in the hardware. + * @internal_data_setup_in_ns: The time, in ns, that the NFC hardware requires + * for data read internal setup. In the Reference + * Manual, see the chapter "High-Speed NAND + * Timing" for more details. + * @max_sample_delay_factor: The maximum sample delay factor that can be + * expressed in the hardware. + * @max_dll_clock_period_in_ns: The maximum period of the GPMI clock that the + * sample delay DLL hardware can possibly work + * with (the DLL is unusable with longer periods). + * If the full-cycle period is greater than HALF + * this value, the DLL must be configured to use + * half-periods. + * @max_dll_delay_in_ns: The maximum amount of delay, in ns, that the + * DLL can implement. + */ +struct timing_threshold { + const unsigned int max_data_setup_cycles; + const unsigned int internal_data_setup_in_ns; + const unsigned int max_sample_delay_factor; + const unsigned int max_dll_clock_period_in_ns; + const unsigned int max_dll_delay_in_ns; +}; + +static struct timing_threshold timing_default_threshold = { + .max_data_setup_cycles = 0xff, + .internal_data_setup_in_ns = 0, + .max_sample_delay_factor = 15, + .max_dll_clock_period_in_ns = 32, + .max_dll_delay_in_ns = 16, +}; + +/* Converts time in nanoseconds to cycles. */ +static unsigned int ns_to_cycles(unsigned int time, + unsigned int period, unsigned int min) +{ + unsigned int k; + + k = (time + period - 1) / period; + return max(k, min); +} + +/* Apply timing to current hardware conditions. */ +static int mxs_nand_compute_hardware_timing(struct mxs_nand_info *info, + struct gpmi_nfc_hardware_timing *hw) +{ + struct timing_threshold *nfc = &timing_default_threshold; + struct nand_chip *nand = &info->nand_chip; + struct nand_timing target = info->timing; + unsigned long clock_frequency_in_hz; + unsigned int clock_period_in_ns; + bool dll_use_half_periods; + unsigned int dll_delay_shift; + unsigned int max_sample_delay_in_ns; + unsigned int address_setup_in_cycles; + unsigned int data_setup_in_ns; + unsigned int data_setup_in_cycles; + unsigned int data_hold_in_cycles; + int ideal_sample_delay_in_ns; + unsigned int sample_delay_factor; + int tEYE; + unsigned int min_prop_delay_in_ns = 5; + unsigned int max_prop_delay_in_ns = 9; + + /* + * If there are multiple chips, we need to relax the timings to allow + * for signal distortion due to higher capacitance. + */ + if (nand->numchips > 2) { + target.data_setup_in_ns += 10; + target.data_hold_in_ns += 10; + target.address_setup_in_ns += 10; + } else if (nand->numchips > 1) { + target.data_setup_in_ns += 5; + target.data_hold_in_ns += 5; + target.address_setup_in_ns += 5; + } + + /* Inspect the clock. */ + clock_frequency_in_hz = clk_get_rate(info->clk); + clock_period_in_ns = NSEC_PER_SEC / clock_frequency_in_hz; + + /* + * The NFC quantizes setup and hold parameters in terms of clock cycles. + * Here, we quantize the setup and hold timing parameters to the + * next-highest clock period to make sure we apply at least the + * specified times. + * + * For data setup and data hold, the hardware interprets a value of zero + * as the largest possible delay. This is not what's intended by a zero + * in the input parameter, so we impose a minimum of one cycle. + */ + data_setup_in_cycles = ns_to_cycles(target.data_setup_in_ns, + clock_period_in_ns, 1); + data_hold_in_cycles = ns_to_cycles(target.data_hold_in_ns, + clock_period_in_ns, 1); + address_setup_in_cycles = ns_to_cycles(target.address_setup_in_ns, + clock_period_in_ns, 0); + + /* + * The clock's period affects the sample delay in a number of ways: + * + * (1) The NFC HAL tells us the maximum clock period the sample delay + * DLL can tolerate. If the clock period is greater than half that + * maximum, we must configure the DLL to be driven by half periods. + * + * (2) We need to convert from an ideal sample delay, in ns, to a + * "sample delay factor," which the NFC uses. This factor depends on + * whether we're driving the DLL with full or half periods. + * Paraphrasing the reference manual: + * + * AD = SDF x 0.125 x RP + * + * where: + * + * AD is the applied delay, in ns. + * SDF is the sample delay factor, which is dimensionless. + * RP is the reference period, in ns, which is a full clock period + * if the DLL is being driven by full periods, or half that if + * the DLL is being driven by half periods. + * + * Let's re-arrange this in a way that's more useful to us: + * + * 8 + * SDF = AD x ---- + * RP + * + * The reference period is either the clock period or half that, so this + * is: + * + * 8 AD x DDF + * SDF = AD x ----- = -------- + * f x P P + * + * where: + * + * f is 1 or 1/2, depending on how we're driving the DLL. + * P is the clock period. + * DDF is the DLL Delay Factor, a dimensionless value that + * incorporates all the constants in the conversion. + * + * DDF will be either 8 or 16, both of which are powers of two. We can + * reduce the cost of this conversion by using bit shifts instead of + * multiplication or division. Thus: + * + * AD << DDS + * SDF = --------- + * P + * + * or + * + * AD = (SDF >> DDS) x P + * + * where: + * + * DDS is the DLL Delay Shift, the logarithm to base 2 of the DDF. + */ + if (clock_period_in_ns > (nfc->max_dll_clock_period_in_ns >> 1)) { + dll_use_half_periods = true; + dll_delay_shift = 3 + 1; + } else { + dll_use_half_periods = false; + dll_delay_shift = 3; + } + + /* + * Compute the maximum sample delay the NFC allows, under current + * conditions. If the clock is running too slowly, no sample delay is + * possible. + */ + if (clock_period_in_ns > nfc->max_dll_clock_period_in_ns) { + max_sample_delay_in_ns = 0; + } else { + /* + * Compute the delay implied by the largest sample delay factor + * the NFC allows. + */ + max_sample_delay_in_ns = + (nfc->max_sample_delay_factor * clock_period_in_ns) >> + dll_delay_shift; + + /* + * Check if the implied sample delay larger than the NFC + * actually allows. + */ + if (max_sample_delay_in_ns > nfc->max_dll_delay_in_ns) + max_sample_delay_in_ns = nfc->max_dll_delay_in_ns; + } + + /* + * Fold the read setup time required by the NFC into the ideal + * sample delay. + */ + ideal_sample_delay_in_ns = target.gpmi_sample_delay_in_ns + + nfc->internal_data_setup_in_ns; + + /* + * The ideal sample delay may be greater than the maximum + * allowed by the NFC. If so, we can trade off sample delay time + * for more data setup time. + * + * In each iteration of the following loop, we add a cycle to + * the data setup time and subtract a corresponding amount from + * the sample delay until we've satisified the constraints or + * can't do any better. + */ + while ((ideal_sample_delay_in_ns > max_sample_delay_in_ns) && + (data_setup_in_cycles < nfc->max_data_setup_cycles)) { + + data_setup_in_cycles++; + ideal_sample_delay_in_ns -= clock_period_in_ns; + + if (ideal_sample_delay_in_ns < 0) + ideal_sample_delay_in_ns = 0; + } + + /* + * Compute the sample delay factor that corresponds most closely + * to the ideal sample delay. If the result is too large for the + * NFC, use the maximum value. + * + * Notice that we use the ns_to_cycles function to compute the + * sample delay factor. We do this because the form of the + * computation is the same as that for calculating cycles. + */ + sample_delay_factor = + ns_to_cycles( + ideal_sample_delay_in_ns << dll_delay_shift, + clock_period_in_ns, 0); + + if (sample_delay_factor > nfc->max_sample_delay_factor) + sample_delay_factor = nfc->max_sample_delay_factor; + + /* Skip to the part where we return our results. */ + goto return_results; + + /* + * If control arrives here, we have more detailed timing information, + * so we can use a better algorithm. + */ + + /* + * Fold the read setup time required by the NFC into the maximum + * propagation delay. + */ + max_prop_delay_in_ns += nfc->internal_data_setup_in_ns; + + /* + * Earlier, we computed the number of clock cycles required to satisfy + * the data setup time. Now, we need to know the actual nanoseconds. + */ + data_setup_in_ns = clock_period_in_ns * data_setup_in_cycles; + + /* + * Compute tEYE, the width of the data eye when reading from the NAND + * Flash. The eye width is fundamentally determined by the data setup + * time, perturbed by propagation delays and some characteristics of the + * NAND Flash device. + * + * start of the eye = max_prop_delay + tREA + * end of the eye = min_prop_delay + tRHOH + data_setup + */ + tEYE = (int)min_prop_delay_in_ns + (int)target.tRHOH_in_ns + + (int)data_setup_in_ns; + + tEYE -= (int)max_prop_delay_in_ns + (int)target.tREA_in_ns; + + /* + * The eye must be open. If it's not, we can try to open it by + * increasing its main forcer, the data setup time. + * + * In each iteration of the following loop, we increase the data setup + * time by a single clock cycle. We do this until either the eye is + * open or we run into NFC limits. + */ + while ((tEYE <= 0) && + (data_setup_in_cycles < nfc->max_data_setup_cycles)) { + /* Give a cycle to data setup. */ + data_setup_in_cycles++; + /* Synchronize the data setup time with the cycles. */ + data_setup_in_ns += clock_period_in_ns; + /* Adjust tEYE accordingly. */ + tEYE += clock_period_in_ns; + } + + /* + * When control arrives here, the eye is open. The ideal time to sample + * the data is in the center of the eye: + * + * end of the eye + start of the eye + * --------------------------------- - data_setup + * 2 + * + * After some algebra, this simplifies to the code immediately below. + */ + ideal_sample_delay_in_ns = + ((int)max_prop_delay_in_ns + + (int)target.tREA_in_ns + + (int)min_prop_delay_in_ns + + (int)target.tRHOH_in_ns - + (int)data_setup_in_ns) >> 1; + + /* + * The following figure illustrates some aspects of a NAND Flash read: + * + * + * __ _____________________________________ + * RDN \_________________/ + * + * <---- tEYE -----> + * /-----------------\ + * Read Data ----------------------------< >--------- + * \-----------------/ + * ^ ^ ^ ^ + * | | | | + * |<--Data Setup -->|<--Delay Time -->| | + * | | | | + * | | | + * | |<-- Quantized Delay Time -->| + * | | | + * + * + * We have some issues we must now address: + * + * (1) The *ideal* sample delay time must not be negative. If it is, we + * jam it to zero. + * + * (2) The *ideal* sample delay time must not be greater than that + * allowed by the NFC. If it is, we can increase the data setup + * time, which will reduce the delay between the end of the data + * setup and the center of the eye. It will also make the eye + * larger, which might help with the next issue... + * + * (3) The *quantized* sample delay time must not fall either before the + * eye opens or after it closes (the latter is the problem + * illustrated in the above figure). + */ + + /* Jam a negative ideal sample delay to zero. */ + if (ideal_sample_delay_in_ns < 0) + ideal_sample_delay_in_ns = 0; + + /* + * Extend the data setup as needed to reduce the ideal sample delay + * below the maximum permitted by the NFC. + */ + while ((ideal_sample_delay_in_ns > max_sample_delay_in_ns) && + (data_setup_in_cycles < nfc->max_data_setup_cycles)) { + + /* Give a cycle to data setup. */ + data_setup_in_cycles++; + /* Synchronize the data setup time with the cycles. */ + data_setup_in_ns += clock_period_in_ns; + /* Adjust tEYE accordingly. */ + tEYE += clock_period_in_ns; + + /* + * Decrease the ideal sample delay by one half cycle, to keep it + * in the middle of the eye. + */ + ideal_sample_delay_in_ns -= (clock_period_in_ns >> 1); + + /* Jam a negative ideal sample delay to zero. */ + if (ideal_sample_delay_in_ns < 0) + ideal_sample_delay_in_ns = 0; + } + + /* + * Compute the sample delay factor that corresponds to the ideal sample + * delay. If the result is too large, then use the maximum allowed + * value. + * + * Notice that we use the ns_to_cycles function to compute the sample + * delay factor. We do this because the form of the computation is the + * same as that for calculating cycles. + */ + sample_delay_factor = + ns_to_cycles(ideal_sample_delay_in_ns << dll_delay_shift, + clock_period_in_ns, 0); + + if (sample_delay_factor > nfc->max_sample_delay_factor) + sample_delay_factor = nfc->max_sample_delay_factor; + + /* + * These macros conveniently encapsulate a computation we'll use to + * continuously evaluate whether or not the data sample delay is inside + * the eye. + */ + #define IDEAL_DELAY ((int) ideal_sample_delay_in_ns) + + #define QUANTIZED_DELAY \ + ((int) ((sample_delay_factor * clock_period_in_ns) >> \ + dll_delay_shift)) + + #define DELAY_ERROR (abs(QUANTIZED_DELAY - IDEAL_DELAY)) + + #define SAMPLE_IS_NOT_WITHIN_THE_EYE (DELAY_ERROR > (tEYE >> 1)) + + /* + * While the quantized sample time falls outside the eye, reduce the + * sample delay or extend the data setup to move the sampling point back + * toward the eye. Do not allow the number of data setup cycles to + * exceed the maximum allowed by the NFC. + */ + while (SAMPLE_IS_NOT_WITHIN_THE_EYE && + (data_setup_in_cycles < nfc->max_data_setup_cycles)) { + /* + * If control arrives here, the quantized sample delay falls + * outside the eye. Check if it's before the eye opens, or after + * the eye closes. + */ + if (QUANTIZED_DELAY > IDEAL_DELAY) { + /* + * If control arrives here, the quantized sample delay + * falls after the eye closes. Decrease the quantized + * delay time and then go back to re-evaluate. + */ + if (sample_delay_factor != 0) + sample_delay_factor--; + continue; + } + + /* + * If control arrives here, the quantized sample delay falls + * before the eye opens. Shift the sample point by increasing + * data setup time. This will also make the eye larger. + */ + + /* Give a cycle to data setup. */ + data_setup_in_cycles++; + /* Synchronize the data setup time with the cycles. */ + data_setup_in_ns += clock_period_in_ns; + /* Adjust tEYE accordingly. */ + tEYE += clock_period_in_ns; + + /* + * Decrease the ideal sample delay by one half cycle, to keep it + * in the middle of the eye. + */ + ideal_sample_delay_in_ns -= (clock_period_in_ns >> 1); + + /* ...and one less period for the delay time. */ + ideal_sample_delay_in_ns -= clock_period_in_ns; + + /* Jam a negative ideal sample delay to zero. */ + if (ideal_sample_delay_in_ns < 0) + ideal_sample_delay_in_ns = 0; + + /* + * We have a new ideal sample delay, so re-compute the quantized + * delay. + */ + sample_delay_factor = + ns_to_cycles( + ideal_sample_delay_in_ns << dll_delay_shift, + clock_period_in_ns, 0); + + if (sample_delay_factor > nfc->max_sample_delay_factor) + sample_delay_factor = nfc->max_sample_delay_factor; + } + + /* Control arrives here when we're ready to return our results. */ +return_results: + hw->data_setup_in_cycles = data_setup_in_cycles; + hw->data_hold_in_cycles = data_hold_in_cycles; + hw->address_setup_in_cycles = address_setup_in_cycles; + hw->use_half_periods = dll_use_half_periods; + hw->sample_delay_factor = sample_delay_factor; + hw->device_busy_timeout = 0x500; + hw->wrn_dly_sel = BV_GPMI_CTRL1_WRN_DLY_SEL_4_TO_8NS; + + /* Return success. */ + return 0; +} + +/* + * <1> Firstly, we should know what's the GPMI-clock means. + * The GPMI-clock is the internal clock in the gpmi nand controller. + * If you set 100MHz to gpmi nand controller, the GPMI-clock's period + * is 10ns. Mark the GPMI-clock's period as GPMI-clock-period. + * + * <2> Secondly, we should know what's the frequency on the nand chip pins. + * The frequency on the nand chip pins is derived from the GPMI-clock. + * We can get it from the following equation: + * + * F = G / (DS + DH) + * + * F : the frequency on the nand chip pins. + * G : the GPMI clock, such as 100MHz. + * DS : GPMI_TIMING0:DATA_SETUP + * DH : GPMI_TIMING0:DATA_HOLD + * + * <3> Thirdly, when the frequency on the nand chip pins is above 33MHz, + * the nand EDO(extended Data Out) timing could be applied. + * The GPMI implements a feedback read strobe to sample the read data. + * The feedback read strobe can be delayed to support the nand EDO timing + * where the read strobe may deasserts before the read data is valid, and + * read data is valid for some time after read strobe. + * + * The following figure illustrates some aspects of a NAND Flash read: + * + * |<---tREA---->| + * | | + * | | | + * |<--tRP-->| | + * | | | + * __ ___|__________________________________ + * RDN \________/ | + * | + * /---------\ + * Read Data --------------< >--------- + * \---------/ + * | | + * |<-D->| + * FeedbackRDN ________ ____________ + * \___________/ + * + * D stands for delay, set in the GPMI_CTRL1:RDN_DELAY. + * + * + * <4> Now, we begin to describe how to compute the right RDN_DELAY. + * + * 4.1) From the aspect of the nand chip pins: + * Delay = (tREA + C - tRP) {1} + * + * tREA : the maximum read access time. From the ONFI nand standards, + * we know that tREA is 16ns in mode 5, tREA is 20ns is mode 4. + * Please check it in : www.onfi.org + * C : a constant for adjust the delay. default is 4. + * tRP : the read pulse width. + * Specified by the GPMI_TIMING0:DATA_SETUP: + * tRP = (GPMI-clock-period) * DATA_SETUP + * + * 4.2) From the aspect of the GPMI nand controller: + * Delay = RDN_DELAY * 0.125 * RP {2} + * + * RP : the DLL reference period. + * if (GPMI-clock-period > DLL_THRETHOLD) + * RP = GPMI-clock-period / 2; + * else + * RP = GPMI-clock-period; + * + * Set the GPMI_CTRL1:HALF_PERIOD if GPMI-clock-period + * is greater DLL_THRETHOLD. In other SOCs, the DLL_THRETHOLD + * is 16ns, but in mx6q, we use 12ns. + * + * 4.3) since {1} equals {2}, we get: + * + * (tREA + 4 - tRP) * 8 + * RDN_DELAY = --------------------- {3} + * RP + * + * 4.4) We only support the fastest asynchronous mode of ONFI nand. + * For some ONFI nand, the mode 4 is the fastest mode; + * while for some ONFI nand, the mode 5 is the fastest mode. + * So we only support the mode 4 and mode 5. It is no need to + * support other modes. + */ +static void mxs_nand_compute_edo_timing(struct mxs_nand_info *info, + struct gpmi_nfc_hardware_timing *hw, int mode) +{ + unsigned long rate = clk_get_rate(info->clk); + int dll_threshold = 12; + unsigned long delay; + unsigned long clk_period; + int t_rea; + int c = 4; + int t_rp; + int rp; + + /* + * [1] for GPMI_TIMING0: + * The async mode requires 40MHz for mode 4, 50MHz for mode 5. + * The GPMI can support 100MHz at most. So if we want to + * get the 40MHz or 50MHz, we have to set DS=1, DH=1. + * Set the ADDRESS_SETUP to 0 in mode 4. + */ + hw->data_setup_in_cycles = 1; + hw->data_hold_in_cycles = 1; + hw->address_setup_in_cycles = ((mode == 5) ? 1 : 0); + + /* [2] for GPMI_TIMING1 */ + hw->device_busy_timeout = 0x9000; + + /* [3] for GPMI_CTRL1 */ + hw->wrn_dly_sel = BV_GPMI_CTRL1_WRN_DLY_SEL_NO_DELAY; + + /* + * Enlarge 10 times for the numerator and denominator in {3}. + * This make us to get more accurate result. + */ + clk_period = NSEC_PER_SEC / (rate / 10); + dll_threshold *= 10; + t_rea = ((mode == 5) ? 16 : 20) * 10; + c *= 10; + + t_rp = clk_period * 1; /* DATA_SETUP is 1 */ + + if (clk_period > dll_threshold) { + hw->use_half_periods = 1; + rp = clk_period / 2; + } else { + hw->use_half_periods = 0; + rp = clk_period; + } + + /* + * Multiply the numerator with 10, we could do a round off: + * 7.8 round up to 8; 7.4 round down to 7. + */ + delay = (((t_rea + c - t_rp) * 8) * 10) / rp; + delay = (delay + 5) / 10; + + hw->sample_delay_factor = delay; +} + +static int mxs_nand_enable_edo_mode(struct mxs_nand_info *info) +{ + struct nand_chip *nand = &info->nand_chip; + struct mtd_info *mtd = &info->mtd; + uint8_t feature[ONFI_SUBFEATURE_PARAM_LEN] = {}; + int ret, mode; + + if (!mxs_nand_is_imx6(info)) + return -ENODEV; + + if (!nand->onfi_version) + return -ENOENT; + + mode = onfi_get_async_timing_mode(nand); + + /* We only support the timing mode 4 and mode 5. */ + if (mode & ONFI_TIMING_MODE_5) + mode = 5; + else if (mode & ONFI_TIMING_MODE_4) + mode = 4; + else + return -EINVAL; + + nand->select_chip(mtd, 0); + + /* [1] send SET FEATURE commond to NAND */ + feature[0] = mode; + + ret = nand->onfi_set_features(mtd, nand, + ONFI_FEATURE_ADDR_TIMING_MODE, feature); + if (ret) + goto err_out; + + /* [2] send GET FEATURE command to double-check the timing mode */ + ret = nand->onfi_get_features(mtd, nand, + ONFI_FEATURE_ADDR_TIMING_MODE, feature); + if (ret || feature[0] != mode) + goto err_out; + + nand->select_chip(mtd, -1); + + /* [3] set the main IO clock, 100MHz for mode 5, 80MHz for mode 4. */ + clk_set_rate(info->clk, (mode == 5) ? 100000000 : 80000000); + + dev_dbg(info->dev, "using asynchronous EDO mode %d\n", mode); + + return mode; + +err_out: + nand->select_chip(mtd, -1); + + return -EINVAL; +} + +static void mxs_nand_setup_timing(struct mxs_nand_info *info) +{ + void __iomem *gpmi_regs = info->io_base; + uint32_t reg; + struct gpmi_nfc_hardware_timing hw; + int mode; + + mode = mxs_nand_enable_edo_mode(info); + if (mode >= 0) + mxs_nand_compute_edo_timing(info, &hw, mode); + else + mxs_nand_compute_hardware_timing(info, &hw); + + writel(GPMI_TIMING0_ADDRESS_SETUP(hw.address_setup_in_cycles) | + GPMI_TIMING0_DATA_HOLD(hw.data_hold_in_cycles) | + GPMI_TIMING0_DATA_SETUP(hw.data_setup_in_cycles), + gpmi_regs + GPMI_TIMING0); + + writel(GPMI_TIMING1_BUSY_TIMEOUT(hw.device_busy_timeout), + gpmi_regs + GPMI_TIMING1); + + reg = readl(gpmi_regs + GPMI_CTRL1); + + reg &= ~GPMI_CTRL1_WRN_DLY(3); + reg |= GPMI_CTRL1_WRN_DLY(hw.wrn_dly_sel); + /* DLL_ENABLE must be set to 0 when setting RDN_DELAY or HALF_PERIOD. */ + reg &= ~GPMI_CTRL1_DLL_ENABLE; + reg &= ~GPMI_CTRL1_RDN_DELAY(0xf); + reg |= GPMI_CTRL1_RDN_DELAY(hw.sample_delay_factor); + reg &= ~GPMI_CTRL1_HALF_PERIOD; + if (hw.use_half_periods) + reg |= GPMI_CTRL1_HALF_PERIOD; + + writel(reg, gpmi_regs + GPMI_CTRL1); + + if (hw.sample_delay_factor) { + writel(GPMI_CTRL1_DLL_ENABLE, gpmi_regs + GPMI_CTRL1_SET); + /* + * After we enable the GPMI DLL, we have to wait 64 clock + * cycles before we can use the GPMI. Assume 1MHz as lowest + * bus clock. + */ + udelay(64); + } +} + static int mxs_nand_probe(struct device_d *dev) { struct resource *iores; @@ -1324,6 +2124,8 @@ static int mxs_nand_probe(struct device_d *dev) return -ENOMEM; } + nand_info->dev = dev; + mxs_nand_probe_dt(dev, nand_info); nand_info->type = type; @@ -1404,6 +2206,8 @@ static int mxs_nand_probe(struct device_d *dev) nand->options |= NAND_NO_SUBPAGE_WRITE; + mxs_nand_setup_timing(nand_info); + /* second phase scan */ err = nand_scan_tail(mtd); if (err) -- 2.8.1 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox