Re: [PATCH 8/8 v2] ARM OMAP2+ GPMC: fix WAITMONITORINGTIME divider bug

[Roger Quadros <rogerq@ti.com>]

Robert,

On 24/02/15 22:05, Robert ABEL wrote:
> The WAITMONITORINGTIME is expressed as a number of GPMC_CLK clock cycles,
> even though the access is defined as asynchronous, and no GPMC_CLK clock
> is provided to the external device. Still, GPMCFCLKDIVIDER is used as a divider
> for the GPMC clock, so it must be programmed to define the
> correct WAITMONITORINGTIME delay.
> 
> This patch correctly computes WAITMONITORINGTIME in GPMC_CLK cycles instead of GPMC_FCLK cycles,
> both during programming (gpmc_cs_set_timings) and during retrieval (gpmc_cs_show_timings).
> 
> Signed-off-by: Robert ABEL <rabel@cit-ec.uni-bielefeld.de>
> ---
>  drivers/memory/omap-gpmc.c | 125 +++++++++++++++++++++++++++++++++++----------
>  1 file changed, 99 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
> index 9cf8d21..6591991 100644
> --- a/drivers/memory/omap-gpmc.c
> +++ b/drivers/memory/omap-gpmc.c
> @@ -170,6 +170,11 @@
>   */
>  #define	GPMC_NR_IRQ		2
>  
> +enum gpmc_clk_domain {
> +	GPMC_CD_FCLK,
> +	GPMC_CD_CLK
> +};
> +
>  struct gpmc_cs_data {
>  	const char *name;
>  
> @@ -268,16 +273,55 @@ static unsigned long gpmc_get_fclk_period(void)
>  	return rate;
>  }
>  
> -static unsigned int gpmc_ns_to_ticks(unsigned int time_ns)
> +/**
> + * gpmc_get_clk_period - get period of selected clock domain in ps
> + * @cs Chip Select Region.
> + * @cd Clock Domain.
> + *
> + * GPMC_CS_CONFIG1 GPMCFCLKDIVIDER for cs has to be setup
> + * prior to calling this function with GPMC_CD_CLK.
> + * 
> + */
> +static unsigned long gpmc_get_clk_period(int cs, enum gpmc_clk_domain cd)
> +{
> +
> +	unsigned long tick_ps = gpmc_get_fclk_period();
> +	u32 l;
> +	int div;
> +
> +	switch (cd) {
> +	case GPMC_CD_CLK:
> +		/* get current clk divider */
> +		l = gpmc_cs_read_reg(cs, GPMC_CS_CONFIG1);
> +		div = (l & 0x03) + 1;
> +		/* get GPMC_CLK period */
> +		tick_ps *= div;
> +		break;
> +	case GPMC_CD_FCLK:
> +		/* FALL-THROUGH */
> +	default:
> +		break;
> +	}
> +
> +	return tick_ps;
> +
> +}
> +
> +static unsigned int gpmc_ns_to_clk_ticks(unsigned int time_ns, int cs, enum gpmc_clk_domain cd)
>  {
>  	unsigned long tick_ps;
>  
>  	/* Calculate in picosecs to yield more exact results */
> -	tick_ps = gpmc_get_fclk_period();
> +	tick_ps = gpmc_get_clk_period(cs, cd);
>  
>  	return (time_ns * 1000 + tick_ps - 1) / tick_ps;
>  }
>  
> +static unsigned int gpmc_ns_to_ticks(unsigned int time_ns)
> +{
> +	return gpmc_ns_to_clk_ticks(time_ns, /* any CS */ 0, GPMC_CD_FCLK);
> +}
> +
>  static unsigned int gpmc_ps_to_ticks(unsigned int time_ps)
>  {
>  	unsigned long tick_ps;
> @@ -288,9 +332,14 @@ static unsigned int gpmc_ps_to_ticks(unsigned int time_ps)
>  	return (time_ps + tick_ps - 1) / tick_ps;
>  }
>  
> +unsigned int gpmc_clk_ticks_to_ns(unsigned ticks, int cs, enum gpmc_clk_domain cd)
> +{
> +	return ticks * gpmc_get_clk_period(cs, cd) / 1000;
> +}
> +
>  unsigned int gpmc_ticks_to_ns(unsigned int ticks)
>  {
> -	return ticks * gpmc_get_fclk_period() / 1000;
> +	return gpmc_clk_ticks_to_ns(ticks, /* any CS */ 0, GPMC_CD_FCLK);
>  }
>  
>  static unsigned int gpmc_ticks_to_ps(unsigned int ticks)
> @@ -346,16 +395,22 @@ static void gpmc_cs_bool_timings(int cs, const struct gpmc_bool_timings *p)
>   * @st_bit  Start Bit
>   * @end_bit End Bit. Must be >= @st_bit.
>   * @name    DTS node name, w/o "gpmc,"
> + * @cd      Clock Domain of timing parameter.
> + * @shift   Parameter value left shifts @shift, which is then printed instead of value.
>   * @raw     Raw Format Option.
>   *          raw format:  gpmc,name = <value>
>   *          tick format: gpmc,name = <value> /&zwj;* x ticks *&zwj;/
>   * @noval   Parameter values equal to 0 are not printed.
> - * @shift   Parameter value left shifts @shift, which is then printed instead of value.
>   *
>   */
> -static int get_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
> -			       bool raw, bool noval, int shift,
> -			       const char *name)
> +static int get_gpmc_timing_reg(
> +	/* timing specifiers */
> +	int cs, int reg, int st_bit, int end_bit,
> +	const char *name, const enum gpmc_clk_domain cd,
> +	/* value transform */
> +	int shift,
> +	/* format specifiers */
> +	bool raw, bool noval)

now that you are rearranging the parameters, "name" parameter should probably be
at the same position (or last) in get_gpmc_timing_reg() and set_gpmc_timing_reg()?
Also clock domain (cd) position could be matched if possible.

>  {
>  	u32 l;
>  	int nr_bits;
> @@ -373,7 +428,7 @@ static int get_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
>  		/* DTS tick format for timings in ns */
>  		unsigned int time_ns;
>  
> -		time_ns = gpmc_ticks_to_ns(l);
> +		time_ns = gpmc_clk_ticks_to_ns(l, cs, cd);
>  		pr_info("gpmc,%s = <%u> /* %i ticks */\n",
>  			name, time_ns, l);
>  	} else {
> @@ -388,13 +443,15 @@ static int get_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
>  	pr_info("cs%i %s: 0x%08x\n", cs, #config, \
>  		gpmc_cs_read_reg(cs, config))
>  #define GPMC_GET_RAW(reg, st, end, field) \
> -	get_gpmc_timing_reg(cs, (reg), (st), (end), 1, 0, 0, field)
> +	get_gpmc_timing_reg(cs, (reg), (st), (end), field, GPMC_CD_FCLK, 0, 1, 0)
>  #define GPMC_GET_RAW_BOOL(reg, st, end, field) \
> -	get_gpmc_timing_reg(cs, (reg), (st), (end), 1, 1, 0, field)
> +	get_gpmc_timing_reg(cs, (reg), (st), (end), field, GPMC_CD_FCLK, 0, 1, 1)
>  #define GPMC_GET_RAW_SHIFT(reg, st, end, shift, field) \
> -	get_gpmc_timing_reg(cs, (reg), (st), (end), 1, 1, (shift), field)
> +	get_gpmc_timing_reg(cs, (reg), (st), (end), field, GPMC_CD_FCLK, (shift), 1, 1)
>  #define GPMC_GET_TICKS(reg, st, end, field) \
> -	get_gpmc_timing_reg(cs, (reg), (st), (end), 0, 0, 0, field)
> +	get_gpmc_timing_reg(cs, (reg), (st), (end), field, GPMC_CD_FCLK, 0, 0, 0)
> +#define GPMC_GET_TICKS_CD(reg, st, end, field, cd) \
> +	get_gpmc_timing_reg(cs, (reg), (st), (end), field, (cd), 0, 0, 0)
>  
>  static void gpmc_show_regs(int cs, const char *desc)
>  {
> @@ -462,7 +519,7 @@ static void gpmc_cs_show_timings(int cs, const char *desc)
>  	GPMC_GET_TICKS(GPMC_CS_CONFIG6, 0, 3, "bus-turnaround-ns");
>  	GPMC_GET_TICKS(GPMC_CS_CONFIG6, 8, 11, "cycle2cycle-delay-ns");
>  
> -	GPMC_GET_TICKS(GPMC_CS_CONFIG1, 18, 19, "wait-monitoring-ns");
> +	GPMC_GET_TICKS_CD(GPMC_CS_CONFIG1, 18, 19, "wait-monitoring-ns", GPMC_CD_CLK);
>  	GPMC_GET_TICKS(GPMC_CS_CONFIG1, 25, 26, "clk-activation-ns");
>  
>  	GPMC_GET_TICKS(GPMC_CS_CONFIG6, 16, 19, "wr-data-mux-bus-ns");
> @@ -474,8 +531,20 @@ static inline void gpmc_cs_show_timings(int cs, const char *desc)
>  }
>  #endif
>  
> +/**
> + * set_gpmc_timing_reg - set a single timing parameter for Chip Select Region.
> + * @cs      Chip Select Region.
> + * @reg     GPMC_CS_CONFIGn register offset.
> + * @st_bit  Start Bit
> + * @end_bit End Bit. Must be >= @st_bit.
> + * @time    Timing parameter in ns.
> + * @cd      Timing parameter clock domain.
> + * @name    Timing parameter name.
> + * @note    Caller is expected to have initialized CONFIG1 GPMCFCLKDIVIDER

@note is not a parameter.

> + *          prior to calling this function with @cd equal to GPMC_CD_CLK.
> + */
>  static int set_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
> -			       int time, const char *name)
> +			       int time, enum gpmc_clk_domain cd, const char *name)
>  {
>  	u32 l;
>  	int ticks, mask, nr_bits;
> @@ -483,12 +552,12 @@ static int set_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
>  	if (time == 0)
>  		ticks = 0;
>  	else
> -		ticks = gpmc_ns_to_ticks(time);
> +		ticks = gpmc_ns_to_clk_ticks(time, cs, cd);
>  	nr_bits = end_bit - st_bit + 1;
>  	mask = (1 << nr_bits) - 1;
>  
>  	if (ticks > mask) {
> -		pr_err("%s: GPMC error! CS%d: %s: %d ns, %d ticks > %d\n",
> +		pr_err("%s: GPMC CS%d: %s %d ns, %d ticks > %d ticks\n",

any reason for removing the "error!" string?

>  		       __func__, cs, name, time, ticks, mask);
>  
>  		return -1;
> @@ -498,7 +567,7 @@ static int set_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
>  #ifdef DEBUG
>  	printk(KERN_INFO
>  		"GPMC CS%d: %-17s: %3d ticks, %3lu ns (was %3i ticks) %3d ns\n",
> -	       cs, name, ticks, gpmc_get_fclk_period() * ticks / 1000,
> +	       cs, name, ticks, gpmc_get_clk_period(cs, cd) * ticks / 1000,
>  			(l >> st_bit) & mask, time);
>  #endif
>  	l &= ~(mask << st_bit);
> @@ -508,11 +577,14 @@ static int set_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit,
>  	return 0;
>  }
>  
> -#define GPMC_SET_ONE(reg, st, end, field) \
> -	if (set_gpmc_timing_reg(cs, (reg), (st), (end),		\
> -			t->field, #field) < 0)			\
> +#define GPMC_SET_ONE_CD(reg, st, end, field, cd) \
> +	if (set_gpmc_timing_reg(cs, (reg), (st), (end), \
> +	    t->field, (cd), #field) < 0)                \
>  		return -1
>  
> +#define GPMC_SET_ONE(reg, st, end, field) \
> +	GPMC_SET_ONE_CD(reg, st, end, field, GPMC_CD_FCLK)
> +
>  /**
>   * gpmc_calc_waitmonitoring_divider - calculate proper GPMCFCLKDIVIDER based on WAITMONITORINGTIME
>   * @wait_monitoring WAITMONITORINGTIME in ns.
> @@ -620,22 +692,23 @@ int gpmc_cs_set_timings(int cs, const struct gpmc_timings *t, const struct gpmc_
>  	GPMC_SET_ONE(GPMC_CS_CONFIG6, 0, 3, bus_turnaround);
>  	GPMC_SET_ONE(GPMC_CS_CONFIG6, 8, 11, cycle2cycle_delay);
>  
> -	GPMC_SET_ONE(GPMC_CS_CONFIG1, 18, 19, wait_monitoring);
> -	GPMC_SET_ONE(GPMC_CS_CONFIG1, 25, 26, clk_activation);
> -
>  	if (gpmc_capability & GPMC_HAS_WR_DATA_MUX_BUS)
>  		GPMC_SET_ONE(GPMC_CS_CONFIG6, 16, 19, wr_data_mux_bus);
>  	if (gpmc_capability & GPMC_HAS_WR_ACCESS)
>  		GPMC_SET_ONE(GPMC_CS_CONFIG6, 24, 28, wr_access);
>  
>  	l = gpmc_cs_read_reg(cs, GPMC_CS_CONFIG1);
> +	l &= ~0x03;
> +	l |= (div - 1);
> +	gpmc_cs_write_reg(cs, GPMC_CS_CONFIG1, l);
> +
> +	GPMC_SET_ONE_CD(GPMC_CS_CONFIG1, 18, 19, wait_monitoring, GPMC_CD_CLK);
> +	GPMC_SET_ONE(GPMC_CS_CONFIG1, 25, 26, clk_activation);
> +
>  #ifdef DEBUG
>  	printk(KERN_INFO "GPMC CS%d CLK period is %lu ns (div %d)\n",
>  			cs, (div * gpmc_get_fclk_period()) / 1000, div);
>  #endif
> -	l &= ~0x03;
> -	l |= (div - 1);
> -	gpmc_cs_write_reg(cs, GPMC_CS_CONFIG1, l);
>  
>  	gpmc_cs_bool_timings(cs, &t->bool_timings);
>  	gpmc_cs_show_timings(cs, "after gpmc_cs_set_timings");
> 

cheers,
-roger