ARM: OMAP2+: gpmc: generic timing calculation

Presently there are three peripherals that gets it timing
by runtime calculation. Those peripherals can work with
frequency scaling that affects gpmc clock. But timing
calculation for them are in different ways.

Here a generic runtime calculation method is proposed. Input
to this function were selected so that they represent timing
variables that are present in peripheral datasheets. Motive
behind this was to achieve DT bindings for the inputs as is.
Even though a few of the tusb6010 timings could not be made
directly related to timings normally found on peripherals,
expressions used were translated to those that could be
justified.

There are possibilities of improving the calculations, like
calculating timing for read & write operations in a more
similar way. Expressions derived here were tested for async
onenand on omap3evm (as vanilla Kernel does not have omap3evm
onenand support, local patch was used). Other peripherals,
tusb6010, smc91x calculations were validated by simulating
on omap3evm.

Regarding "we_on" for onenand async, it was found that even
for muxed address/data, it need not be greater than
"adv_wr_off", but rather could be derived from write setup
time for peripheral from start of access time, hence would
more be in line with peripheral timings. With this method
it was working fine. If it is required in some cases to
have "we_on" same as "wr_data_mux_bus" (i.e. greater than
"adv_wr_off"), another variable could be added to indicate
it. But such a requirement is not expected though.

It has been observed that "adv_rd_off" & "adv_wr_off" are
currently calculated by adding an offset over "oe_on" and
"we_on" respectively in the case of smc91x. But peripheral
datasheet does not specify so and so "adv_rd(wr)_off" has
been derived (to be specific, made ignorant of "oe_on" and
"we_on") observing datasheet rather than adding an offset.
Hence this generic routine is expected to work for smc91x
(91C96 RX51 board). This was verified on smsc911x (9220 on
OMAP3EVM) - a similar ethernet controller.

Timings are calculated in ps to prevent rounding errors and
converted to ns at final stage so that these values can be
directly fed to gpmc_cs_set_timings(). gpmc_cs_set_timings()
would be modified to take ps once all custom timing routines
are replaced by the generic routine, at the same time
generic timing routine would be modified to provide timings
in ps. struct gpmc_timings field types are upgraded from
u16 => u32 so that it can hold ps values.

Whole of this exercise is being done to achieve driver and
DT conversion. If timings could not be calculated in a
peripheral agnostic way, either gpmc driver would have to
be peripheral gnostic or a wrapper arrangement over gpmc
driver would be required.

Signed-off-by: Afzal Mohammed <afzal@ti.com>

1 files changed, 325 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index 5619d1b4866..65468f6d7f0 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -230,6 +230,18 @@ unsigned int gpmc_round_ns_to_ticks(unsigned int time_ns)
 	return ticks * gpmc_get_fclk_period() / 1000;
 }
 
+static unsigned int gpmc_ticks_to_ps(unsigned int ticks)
+{
+	return ticks * gpmc_get_fclk_period();
+}
+
+static unsigned int gpmc_round_ps_to_ticks(unsigned int time_ps)
+{
+	unsigned long ticks = gpmc_ps_to_ticks(time_ps);
+
+	return ticks * gpmc_get_fclk_period();
+}
+
 static inline void gpmc_cs_modify_reg(int cs, int reg, u32 mask, bool value)
 {
 	u32 l;
@@ -796,6 +808,319 @@ static int __devinit gpmc_mem_init(void)
 	return 0;
 }
 
+static u32 gpmc_round_ps_to_sync_clk(u32 time_ps, u32 sync_clk)
+{
+	u32 temp;
+	int div;
+
+	div = gpmc_calc_divider(sync_clk);
+	temp = gpmc_ps_to_ticks(time_ps);
+	temp = (temp + div - 1) / div;
+	return gpmc_ticks_to_ps(temp * div);
+}
+
+/* XXX: can the cycles be avoided ? */
+static int gpmc_calc_sync_read_timings(struct gpmc_timings *gpmc_t,
+				struct gpmc_device_timings *dev_t)
+{
+	bool mux = dev_t->mux;
+	u32 temp;
+
+	/* adv_rd_off */
+	temp = dev_t->t_avdp_r;
+	/* XXX: mux check required ? */
+	if (mux) {
+		/* XXX: t_avdp not to be required for sync, only added for tusb
+		 * this indirectly necessitates requirement of t_avdp_r and
+		 * t_avdp_w instead of having a single t_avdp
+		 */
+		temp = max_t(u32, temp,	gpmc_t->clk_activation + dev_t->t_avdh);
+		temp = max_t(u32, gpmc_t->adv_on + gpmc_ticks_to_ps(1), temp);
+	}
+	gpmc_t->adv_rd_off = gpmc_round_ps_to_ticks(temp);
+
+	/* oe_on */
+	temp = dev_t->t_oeasu; /* XXX: remove this ? */
+	if (mux) {
+		temp = max_t(u32, temp,	gpmc_t->clk_activation + dev_t->t_ach);
+		temp = max_t(u32, temp, gpmc_t->adv_rd_off +
+				gpmc_ticks_to_ps(dev_t->cyc_aavdh_oe));
+	}
+	gpmc_t->oe_on = gpmc_round_ps_to_ticks(temp);
+
+	/* access */
+	/* XXX: any scope for improvement ?, by combining oe_on
+	 * and clk_activation, need to check whether
+	 * access = clk_activation + round to sync clk ?
+	 */
+	temp = max_t(u32, dev_t->t_iaa,	dev_t->cyc_iaa * gpmc_t->sync_clk);
+	temp += gpmc_t->clk_activation;
+	if (dev_t->cyc_oe)
+		temp = max_t(u32, temp, gpmc_t->oe_on +
+				gpmc_ticks_to_ps(dev_t->cyc_oe));
+	gpmc_t->access = gpmc_round_ps_to_ticks(temp);
+
+	gpmc_t->oe_off = gpmc_t->access + gpmc_ticks_to_ps(1);
+	gpmc_t->cs_rd_off = gpmc_t->oe_off;
+
+	/* rd_cycle */
+	temp = max_t(u32, dev_t->t_cez_r, dev_t->t_oez);
+	temp = gpmc_round_ps_to_sync_clk(temp, gpmc_t->sync_clk) +
+							gpmc_t->access;
+	/* XXX: barter t_ce_rdyz with t_cez_r ? */
+	if (dev_t->t_ce_rdyz)
+		temp = max_t(u32, temp,	gpmc_t->cs_rd_off + dev_t->t_ce_rdyz);
+	gpmc_t->rd_cycle = gpmc_round_ps_to_ticks(temp);
+
+	return 0;
+}
+
+static int gpmc_calc_sync_write_timings(struct gpmc_timings *gpmc_t,
+				struct gpmc_device_timings *dev_t)
+{
+	bool mux = dev_t->mux;
+	u32 temp;
+
+	/* adv_wr_off */
+	temp = dev_t->t_avdp_w;
+	if (mux) {
+		temp = max_t(u32, temp,
+			gpmc_t->clk_activation + dev_t->t_avdh);
+		temp = max_t(u32, gpmc_t->adv_on + gpmc_ticks_to_ps(1), temp);
+	}
+	gpmc_t->adv_wr_off = gpmc_round_ps_to_ticks(temp);
+
+	/* wr_data_mux_bus */
+	temp = max_t(u32, dev_t->t_weasu,
+			gpmc_t->clk_activation + dev_t->t_rdyo);
+	/* XXX: shouldn't mux be kept as a whole for wr_data_mux_bus ?,
+	 * and in that case remember to handle we_on properly
+	 */
+	if (mux) {
+		temp = max_t(u32, temp,
+			gpmc_t->adv_wr_off + dev_t->t_aavdh);
+		temp = max_t(u32, temp, gpmc_t->adv_wr_off +
+				gpmc_ticks_to_ps(dev_t->cyc_aavdh_we));
+	}
+	gpmc_t->wr_data_mux_bus = gpmc_round_ps_to_ticks(temp);
+
+	/* we_on */
+	if (gpmc_capability & GPMC_HAS_WR_DATA_MUX_BUS)
+		gpmc_t->we_on = gpmc_round_ps_to_ticks(dev_t->t_weasu);
+	else
+		gpmc_t->we_on = gpmc_t->wr_data_mux_bus;
+
+	/* wr_access */
+	/* XXX: gpmc_capability check reqd ? , even if not, will not harm */
+	gpmc_t->wr_access = gpmc_t->access;
+
+	/* we_off */
+	temp = gpmc_t->we_on + dev_t->t_wpl;
+	temp = max_t(u32, temp,
+			gpmc_t->wr_access + gpmc_ticks_to_ps(1));
+	temp = max_t(u32, temp,
+		gpmc_t->we_on + gpmc_ticks_to_ps(dev_t->cyc_wpl));
+	gpmc_t->we_off = gpmc_round_ps_to_ticks(temp);
+
+	gpmc_t->cs_wr_off = gpmc_round_ps_to_ticks(gpmc_t->we_off +
+							dev_t->t_wph);
+
+	/* wr_cycle */
+	temp = gpmc_round_ps_to_sync_clk(dev_t->t_cez_w, gpmc_t->sync_clk);
+	temp += gpmc_t->wr_access;
+	/* XXX: barter t_ce_rdyz with t_cez_w ? */
+	if (dev_t->t_ce_rdyz)
+		temp = max_t(u32, temp,
+				 gpmc_t->cs_wr_off + dev_t->t_ce_rdyz);
+	gpmc_t->wr_cycle = gpmc_round_ps_to_ticks(temp);
+
+	return 0;
+}
+
+static int gpmc_calc_async_read_timings(struct gpmc_timings *gpmc_t,
+				struct gpmc_device_timings *dev_t)
+{
+	bool mux = dev_t->mux;
+	u32 temp;
+
+	/* adv_rd_off */
+	temp = dev_t->t_avdp_r;
+	if (mux)
+		temp = max_t(u32, gpmc_t->adv_on + gpmc_ticks_to_ps(1), temp);
+	gpmc_t->adv_rd_off = gpmc_round_ps_to_ticks(temp);
+
+	/* oe_on */
+	temp = dev_t->t_oeasu;
+	if (mux)
+		temp = max_t(u32, temp,
+			gpmc_t->adv_rd_off + dev_t->t_aavdh);
+	gpmc_t->oe_on = gpmc_round_ps_to_ticks(temp);
+
+	/* access */
+	temp = max_t(u32, dev_t->t_iaa, /* XXX: remove t_iaa in async ? */
+				gpmc_t->oe_on + dev_t->t_oe);
+	temp = max_t(u32, temp,
+				gpmc_t->cs_on + dev_t->t_ce);
+	temp = max_t(u32, temp,
+				gpmc_t->adv_on + dev_t->t_aa);
+	gpmc_t->access = gpmc_round_ps_to_ticks(temp);
+
+	gpmc_t->oe_off = gpmc_t->access + gpmc_ticks_to_ps(1);
+	gpmc_t->cs_rd_off = gpmc_t->oe_off;
+
+	/* rd_cycle */
+	temp = max_t(u32, dev_t->t_rd_cycle,
+			gpmc_t->cs_rd_off + dev_t->t_cez_r);
+	temp = max_t(u32, temp, gpmc_t->oe_off + dev_t->t_oez);
+	gpmc_t->rd_cycle = gpmc_round_ps_to_ticks(temp);
+
+	return 0;
+}
+
+static int gpmc_calc_async_write_timings(struct gpmc_timings *gpmc_t,
+				struct gpmc_device_timings *dev_t)
+{
+	bool mux = dev_t->mux;
+	u32 temp;
+
+	/* adv_wr_off */
+	temp = dev_t->t_avdp_w;
+	if (mux)
+		temp = max_t(u32, gpmc_t->adv_on + gpmc_ticks_to_ps(1), temp);
+	gpmc_t->adv_wr_off = gpmc_round_ps_to_ticks(temp);
+
+	/* wr_data_mux_bus */
+	temp = dev_t->t_weasu;
+	if (mux) {
+		temp = max_t(u32, temp,	gpmc_t->adv_wr_off + dev_t->t_aavdh);
+		temp = max_t(u32, temp, gpmc_t->adv_wr_off +
+				gpmc_ticks_to_ps(dev_t->cyc_aavdh_we));
+	}
+	gpmc_t->wr_data_mux_bus = gpmc_round_ps_to_ticks(temp);
+
+	/* we_on */
+	if (gpmc_capability & GPMC_HAS_WR_DATA_MUX_BUS)
+		gpmc_t->we_on = gpmc_round_ps_to_ticks(dev_t->t_weasu);
+	else
+		gpmc_t->we_on = gpmc_t->wr_data_mux_bus;
+
+	/* we_off */
+	temp = gpmc_t->we_on + dev_t->t_wpl;
+	gpmc_t->we_off = gpmc_round_ps_to_ticks(temp);
+
+	gpmc_t->cs_wr_off = gpmc_round_ps_to_ticks(gpmc_t->we_off +
+							dev_t->t_wph);
+
+	/* wr_cycle */
+	temp = max_t(u32, dev_t->t_wr_cycle,
+				gpmc_t->cs_wr_off + dev_t->t_cez_w);
+	gpmc_t->wr_cycle = gpmc_round_ps_to_ticks(temp);
+
+	return 0;
+}
+
+static int gpmc_calc_sync_common_timings(struct gpmc_timings *gpmc_t,
+			struct gpmc_device_timings *dev_t)
+{
+	u32 temp;
+
+	gpmc_t->sync_clk = gpmc_calc_divider(dev_t->clk) *
+						gpmc_get_fclk_period();
+
+	gpmc_t->page_burst_access = gpmc_round_ps_to_sync_clk(
+					dev_t->t_bacc,
+					gpmc_t->sync_clk);
+
+	temp = max_t(u32, dev_t->t_ces, dev_t->t_avds);
+	gpmc_t->clk_activation = gpmc_round_ps_to_ticks(temp);
+
+	if (gpmc_calc_divider(gpmc_t->sync_clk) != 1)
+		return 0;
+
+	if (dev_t->ce_xdelay)
+		gpmc_t->bool_timings.cs_extra_delay = true;
+	if (dev_t->avd_xdelay)
+		gpmc_t->bool_timings.adv_extra_delay = true;
+	if (dev_t->oe_xdelay)
+		gpmc_t->bool_timings.oe_extra_delay = true;
+	if (dev_t->we_xdelay)
+		gpmc_t->bool_timings.we_extra_delay = true;
+
+	return 0;
+}
+
+static int gpmc_calc_common_timings(struct gpmc_timings *gpmc_t,
+			struct gpmc_device_timings *dev_t)
+{
+	u32 temp;
+
+	/* cs_on */
+	gpmc_t->cs_on = gpmc_round_ps_to_ticks(dev_t->t_ceasu);
+
+	/* adv_on */
+	temp = dev_t->t_avdasu;
+	if (dev_t->t_ce_avd)
+		temp = max_t(u32, temp,
+				gpmc_t->cs_on + dev_t->t_ce_avd);
+	gpmc_t->adv_on = gpmc_round_ps_to_ticks(temp);
+
+	if (dev_t->sync_write || dev_t->sync_read)
+		gpmc_calc_sync_common_timings(gpmc_t, dev_t);
+
+	return 0;
+}
+
+/* TODO: remove this function once all peripherals are confirmed to
+ * work with generic timing. Simultaneously gpmc_cs_set_timings()
+ * has to be modified to handle timings in ps instead of ns
+*/
+static void gpmc_convert_ps_to_ns(struct gpmc_timings *t)
+{
+	t->cs_on /= 1000;
+	t->cs_rd_off /= 1000;
+	t->cs_wr_off /= 1000;
+	t->adv_on /= 1000;
+	t->adv_rd_off /= 1000;
+	t->adv_wr_off /= 1000;
+	t->we_on /= 1000;
+	t->we_off /= 1000;
+	t->oe_on /= 1000;
+	t->oe_off /= 1000;
+	t->page_burst_access /= 1000;
+	t->access /= 1000;
+	t->rd_cycle /= 1000;
+	t->wr_cycle /= 1000;
+	t->bus_turnaround /= 1000;
+	t->cycle2cycle_delay /= 1000;
+	t->wait_monitoring /= 1000;
+	t->clk_activation /= 1000;
+	t->wr_access /= 1000;
+	t->wr_data_mux_bus /= 1000;
+}
+
+int gpmc_calc_timings(struct gpmc_timings *gpmc_t,
+			struct gpmc_device_timings *dev_t)
+{
+	memset(gpmc_t, 0, sizeof(*gpmc_t));
+
+	gpmc_calc_common_timings(gpmc_t, dev_t);
+
+	if (dev_t->sync_read)
+		gpmc_calc_sync_read_timings(gpmc_t, dev_t);
+	else
+		gpmc_calc_async_read_timings(gpmc_t, dev_t);
+
+	if (dev_t->sync_write)
+		gpmc_calc_sync_write_timings(gpmc_t, dev_t);
+	else
+		gpmc_calc_async_write_timings(gpmc_t, dev_t);
+
+	/* TODO: remove, see function definition */
+	gpmc_convert_ps_to_ns(gpmc_t);
+
+	return 0;
+}
+
 static __devinit int gpmc_probe(struct platform_device *pdev)
 {
 	int rc;