[PATCH v4 5/5] mtd: rawnand: denali: optimize timing parameters for data interface

Masahiro Yamada
2018-06-22T16:09:32Z

This commit improves the ->setup_data_interface() hook.

The denali_setup_data_interface() needs the frequency of clk_x
and the ratio of clk_x / clk.

The latter is currently hardcoded in the driver, like this:

#define DENALI_CLK_X_MULT 6

The IP datasheet requires that clk_x / clk be 4, 5, or 6. I just
chose 6 because it is the most defensive value, but it is not optimal.
By getting the clock rate of both "clk" and "clk_x", the driver can
compute the timing values more precisely.

To not break the existing platforms, the fallback value, 50 MHz is
provided. It is true for all upstreamed platforms.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Tested-by: Richard Weinberger <richard@nod.at>
---

Changes in v4: None
Changes in v3: None
Changes in v2:
- Split patches into sensible chunks

drivers/mtd/nand/raw/denali.c | 49 +++++++++++++++++++--------------------
drivers/mtd/nand/raw/denali.h | 1 +
drivers/mtd/nand/raw/denali_dt.c | 2 ++
drivers/mtd/nand/raw/denali_pci.c | 1 +
4 files changed, 28 insertions(+), 25 deletions(-)

diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
index 2a302a1..2de46d4 100644
--- a/drivers/mtd/nand/raw/denali.c
+++ b/drivers/mtd/nand/raw/denali.c
@@ -51,14 +51,6 @@ MODULE_LICENSE("GPL");
#define DENALI_INVALID_BANK -1
#define DENALI_NR_BANKS 4

-/*
- * The bus interface clock, clk_x, is phase aligned with the core clock. The
- * clk_x is an integral multiple N of the core clk. The value N is configured
- * at IP delivery time, and its available value is 4, 5, or 6. We need to align
- * to the largest value to make it work with any possible configuration.
- */
-#define DENALI_CLK_X_MULT 6
-
static inline struct denali_nand_info *mtd_to_denali(struct mtd_info *mtd)
{
return container_of(mtd_to_nand(mtd), struct denali_nand_info, nand);
@@ -954,7 +946,7 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
{
struct denali_nand_info *denali = mtd_to_denali(mtd);
const struct nand_sdr_timings *timings;
- unsigned long t_clk;
+ unsigned long t_x, mult_x;
int acc_clks, re_2_we, re_2_re, we_2_re, addr_2_data;
int rdwr_en_lo, rdwr_en_hi, rdwr_en_lo_hi, cs_setup;
int addr_2_data_mask;
@@ -965,15 +957,24 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
return PTR_ERR(timings);

/* clk_x period in picoseconds */
- t_clk = DIV_ROUND_DOWN_ULL(1000000000000ULL, denali->clk_x_rate);
- if (!t_clk)
+ t_x = DIV_ROUND_DOWN_ULL(1000000000000ULL, denali->clk_x_rate);
+ if (!t_x)
+ return -EINVAL;
+
+ /*
+ * The bus interface clock, clk_x, is phase aligned with the core clock.
+ * The clk_x is an integral multiple N of the core clk. The value N is
+ * configured at IP delivery time, and its available value is 4, 5, 6.
+ */
+ mult_x = DIV_ROUND_CLOSEST_ULL(denali->clk_x_rate, denali->clk_rate);
+ if (mult_x < 4 || mult_x > 6)
return -EINVAL;

if (chipnr == NAND_DATA_IFACE_CHECK_ONLY)
return 0;

/* tREA -> ACC_CLKS */
- acc_clks = DIV_ROUND_UP(timings->tREA_max, t_clk);
+ acc_clks = DIV_ROUND_UP(timings->tREA_max, t_x);
acc_clks = min_t(int, acc_clks, ACC_CLKS__VALUE);

tmp = ioread32(denali->reg + ACC_CLKS);
@@ -982,7 +983,7 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
iowrite32(tmp, denali->reg + ACC_CLKS);

/* tRWH -> RE_2_WE */
- re_2_we = DIV_ROUND_UP(timings->tRHW_min, t_clk);
+ re_2_we = DIV_ROUND_UP(timings->tRHW_min, t_x);
re_2_we = min_t(int, re_2_we, RE_2_WE__VALUE);

tmp = ioread32(denali->reg + RE_2_WE);
@@ -991,7 +992,7 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
iowrite32(tmp, denali->reg + RE_2_WE);

/* tRHZ -> RE_2_RE */
- re_2_re = DIV_ROUND_UP(timings->tRHZ_max, t_clk);
+ re_2_re = DIV_ROUND_UP(timings->tRHZ_max, t_x);
re_2_re = min_t(int, re_2_re, RE_2_RE__VALUE);

tmp = ioread32(denali->reg + RE_2_RE);
@@ -1005,8 +1006,7 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
* With WE_2_RE properly set, the Denali controller automatically takes
* care of the delay; the driver need not set NAND_WAIT_TCCS.
*/
- we_2_re = DIV_ROUND_UP(max(timings->tCCS_min, timings->tWHR_min),
- t_clk);
+ we_2_re = DIV_ROUND_UP(max(timings->tCCS_min, timings->tWHR_min), t_x);
we_2_re = min_t(int, we_2_re, TWHR2_AND_WE_2_RE__WE_2_RE);

tmp = ioread32(denali->reg + TWHR2_AND_WE_2_RE);
@@ -1021,7 +1021,7 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
if (denali->revision < 0x0501)
addr_2_data_mask >>= 1;

- addr_2_data = DIV_ROUND_UP(timings->tADL_min, t_clk);
+ addr_2_data = DIV_ROUND_UP(timings->tADL_min, t_x);
addr_2_data = min_t(int, addr_2_data, addr_2_data_mask);

tmp = ioread32(denali->reg + TCWAW_AND_ADDR_2_DATA);
@@ -1031,7 +1031,7 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,

/* tREH, tWH -> RDWR_EN_HI_CNT */
rdwr_en_hi = DIV_ROUND_UP(max(timings->tREH_min, timings->tWH_min),
- t_clk);
+ t_x);
rdwr_en_hi = min_t(int, rdwr_en_hi, RDWR_EN_HI_CNT__VALUE);

tmp = ioread32(denali->reg + RDWR_EN_HI_CNT);
@@ -1040,11 +1040,10 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
iowrite32(tmp, denali->reg + RDWR_EN_HI_CNT);

/* tRP, tWP -> RDWR_EN_LO_CNT */
- rdwr_en_lo = DIV_ROUND_UP(max(timings->tRP_min, timings->tWP_min),
- t_clk);
+ rdwr_en_lo = DIV_ROUND_UP(max(timings->tRP_min, timings->tWP_min), t_x);
rdwr_en_lo_hi = DIV_ROUND_UP(max(timings->tRC_min, timings->tWC_min),
- t_clk);
- rdwr_en_lo_hi = max(rdwr_en_lo_hi, DENALI_CLK_X_MULT);
+ t_x);
+ rdwr_en_lo_hi = max_t(int, rdwr_en_lo_hi, mult_x);
rdwr_en_lo = max(rdwr_en_lo, rdwr_en_lo_hi - rdwr_en_hi);
rdwr_en_lo = min_t(int, rdwr_en_lo, RDWR_EN_LO_CNT__VALUE);

@@ -1054,8 +1053,8 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
iowrite32(tmp, denali->reg + RDWR_EN_LO_CNT);

/* tCS, tCEA -> CS_SETUP_CNT */
- cs_setup = max3((int)DIV_ROUND_UP(timings->tCS_min, t_clk) - rdwr_en_lo,
- (int)DIV_ROUND_UP(timings->tCEA_max, t_clk) - acc_clks,
+ cs_setup = max3((int)DIV_ROUND_UP(timings->tCS_min, t_x) - rdwr_en_lo,
+ (int)DIV_ROUND_UP(timings->tCEA_max, t_x) - acc_clks,
0);
cs_setup = min_t(int, cs_setup, CS_SETUP_CNT__VALUE);

@@ -1282,7 +1281,7 @@ int denali_init(struct denali_nand_info *denali)
}

/* clk rate info is needed for setup_data_interface */
- if (denali->clk_x_rate)
+ if (denali->clk_rate && denali->clk_x_rate)
chip->setup_data_interface = denali_setup_data_interface;

ret = nand_scan_ident(mtd, denali->max_banks, NULL);
diff --git a/drivers/mtd/nand/raw/denali.h b/drivers/mtd/nand/raw/denali.h
index 9ad33d2..1f8feaf 100644
--- a/drivers/mtd/nand/raw/denali.h
+++ b/drivers/mtd/nand/raw/denali.h
@@ -300,6 +300,7 @@

struct denali_nand_info {
struct nand_chip nand;
+ unsigned long clk_rate; /* core clock rate */
unsigned long clk_x_rate; /* bus interface clock rate */
int active_bank; /* currently selected bank */
struct device *dev;
diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
index afaae37..0faaad0 100644
--- a/drivers/mtd/nand/raw/denali_dt.c
+++ b/drivers/mtd/nand/raw/denali_dt.c
@@ -150,6 +150,7 @@ static int denali_dt_probe(struct platform_device *pdev)
goto out_disable_clk_x;

if (dt->clk_x) {
+ denali->clk_rate = clk_get_rate(dt->clk);
denali->clk_x_rate = clk_get_rate(dt->clk_x);
} else {
/*
@@ -158,6 +159,7 @@ static int denali_dt_probe(struct platform_device *pdev)
*/
dev_notice(dev,
"necessary clock is missing. default clock rates are used.\n");
+ denali->clk_rate = 50000000;
denali->clk_x_rate = 200000000;
}

diff --git a/drivers/mtd/nand/raw/denali_pci.c b/drivers/mtd/nand/raw/denali_pci.c
index 49cb3e1..7c8efc4 100644
--- a/drivers/mtd/nand/raw/denali_pci.c
+++ b/drivers/mtd/nand/raw/denali_pci.c
@@ -73,6 +73,7 @@ static int denali_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
denali->irq = dev->irq;
denali->ecc_caps = &denali_pci_ecc_caps;
denali->nand.ecc.options |= NAND_ECC_MAXIMIZE;
+ denali->clk_rate = 50000000; /* 50 MHz */
denali->clk_x_rate = 200000000; /* 200 MHz */

ret = pci_request_regions(dev, DENALI_NAND_NAME);
--
2.7.4