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 <s.hauer@xxxxxxxxxxxxxx>
---
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
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