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mtd: gpmi: add EDO feature for imx6q 

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 in
the EDO timing mode.

This patch adds the EDO feature for the gpmi-nand driver.

For some onfi nand chips, the mode 4 is the fastest;
while for other onfi nand chips, the mode 5 is the fastest.
This patch only adds the support for the fastest asynchronous timing mode.
So this patch only supports the mode 4 and mode 5.

I tested several Micron's ONFI nand chips with EDO enabled,
take Micron MT29F32G08MAA for example (in mode 5, 100MHz):

1) The test result BEFORE we add the EDO feature:
	=================================================
	mtd_speedtest: MTD device: 2
	mtd_speedtest: MTD device size 209715200, eraseblock size 524288,
				page size 4096, count of eraseblocks 400,
				pages per eraseblock 128, OOB size 218
	.......................................
	mtd_speedtest: testing eraseblock read speed
	mtd_speedtest: eraseblock read speed is 3632 KiB/s
	.......................................
	mtd_speedtest: testing page read speed
	mtd_speedtest: page read speed is 3554 KiB/s
	.......................................
	mtd_speedtest: testing 2 page read speed
	mtd_speedtest: 2 page read speed is 3592 KiB/s
	.......................................
	=================================================

2) The test result AFTER we add the EDO feature:
	=================================================
	mtd_speedtest: MTD device: 2
	mtd_speedtest: MTD device size 209715200, eraseblock size 524288,
				page size 4096, count of eraseblocks 400,
				pages per eraseblock 128, OOB size 218
	.......................................
	mtd_speedtest: testing eraseblock read speed
	mtd_speedtest: eraseblock read speed is 19555 KiB/s
	.......................................
	mtd_speedtest: testing page read speed
	mtd_speedtest: page read speed is 17319 KiB/s
	.......................................
	mtd_speedtest: testing 2 page read speed
	mtd_speedtest: 2 page read speed is 18339 KiB/s
	.......................................
	=================================================

3) The read data performance is much improved by more then 5 times.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Huang Shijie 2012-09-13 14:57:59 +08:00 committed by David Woodhouse
parent e1ca95e3a9
commit 995fbbf563
3 changed files with 227 additions and 1 deletions
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214
drivers/mtd/nand/gpmi-nand/gpmi-lib.c
View File

@ -737,6 +737,215 @@ return_results:
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_HW_GPMI_TIMING0:DATA_SETUP
* DH : GPMI_HW_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 HW_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 HW_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 HW_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 gpmi_compute_edo_timing(struct gpmi_nand_data *this,
struct gpmi_nfc_hardware_timing *hw)
{
struct resources *r = &this->resources;
unsigned long rate = clk_get_rate(r->clock[0]);
int mode = this->timing_mode;
int dll_threshold = 16; /* in ns */
unsigned long delay;
unsigned long clk_period;
int t_rea;
int c = 4;
int t_rp;
int rp;
/*
* [1] for GPMI_HW_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_HW_GPMI_TIMING1 */
hw->device_busy_timeout = 0x9000;
/* [3] for GPMI_HW_GPMI_CTRL1 */
hw->wrn_dly_sel = BV_GPMI_CTRL1_WRN_DLY_SEL_NO_DELAY;
if (GPMI_IS_MX6Q(this))
dll_threshold = 12;
/*
* 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 enable_edo_mode(struct gpmi_nand_data *this, int mode)
{
struct resources *r = &this->resources;
struct nand_chip *nand = &this->nand;
struct mtd_info *mtd = &this->mtd;
uint8_t feature[ONFI_SUBFEATURE_PARAM_LEN] = {};
unsigned long rate;
int ret;
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 */
memset(feature, 0, ONFI_SUBFEATURE_PARAM_LEN);
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. */
rate = (mode == 5) ? 100000000 : 80000000;
clk_set_rate(r->clock[0], rate);
this->flags |= GPMI_ASYNC_EDO_ENABLED;
this->timing_mode = mode;
dev_info(this->dev, "enable the asynchronous EDO mode %d\n", mode);
return 0;
err_out:
nand->select_chip(mtd, -1);
dev_err(this->dev, "mode:%d ,failed in set feature.\n", mode);
return -EINVAL;
}
int gpmi_extra_init(struct gpmi_nand_data *this)
{
struct nand_chip *chip = &this->nand;
/* Enable the asynchronous EDO feature. */
if (GPMI_IS_MX6Q(this) && chip->onfi_version) {
int mode = onfi_get_async_timing_mode(chip);
/* 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 0;
return enable_edo_mode(this, mode);
}
return 0;
}
/* Begin the I/O */
void gpmi_begin(struct gpmi_nand_data *this)
{
@ -755,7 +964,10 @@ void gpmi_begin(struct gpmi_nand_data *this)
goto err_out;
}
gpmi_nfc_compute_hardware_timing(this, &hw);
if (this->flags & GPMI_ASYNC_EDO_ENABLED)
gpmi_compute_edo_timing(this, &hw);
else
gpmi_nfc_compute_hardware_timing(this, &hw);
/* [1] Set HW_GPMI_TIMING0 */
reg = BF_GPMI_TIMING0_ADDRESS_SETUP(hw.address_setup_in_cycles) |

8
drivers/mtd/nand/gpmi-nand/gpmi-nand.c
View File

@ -1517,6 +1517,14 @@ static int gpmi_scan_bbt(struct mtd_info *mtd)
if (ret)
return ret;
/*
* Can we enable the extra features? such as EDO or Sync mode.
*
* We do not check the return value now. That's means if we fail in
* enable the extra features, we still can run in the normal way.
*/
gpmi_extra_init(this);
/* use the default BBT implementation */
return nand_default_bbt(mtd);
}

6
drivers/mtd/nand/gpmi-nand/gpmi-nand.h
View File

@ -122,6 +122,10 @@ struct nand_timing {
};
struct gpmi_nand_data {
/* flags */
#define GPMI_ASYNC_EDO_ENABLED (1 << 0)
int flags;
/* System Interface */
struct device *dev;
struct platform_device *pdev;
@ -132,6 +136,7 @@ struct gpmi_nand_data {
/* Flash Hardware */
struct nand_timing timing;
int timing_mode;
/* BCH */
struct bch_geometry bch_geometry;
@ -259,6 +264,7 @@ extern int start_dma_with_bch_irq(struct gpmi_nand_data *,
/* GPMI-NAND helper function library */
extern int gpmi_init(struct gpmi_nand_data *);
extern int gpmi_extra_init(struct gpmi_nand_data *);
extern void gpmi_clear_bch(struct gpmi_nand_data *);
extern void gpmi_dump_info(struct gpmi_nand_data *);
extern int bch_set_geometry(struct gpmi_nand_data *);