* Re: [PATCH 5/7 v4] mmc: sh_mmcif: calculate best clock with parent clock
[not found] ` <874mo7gsza.wl%kuninori.morimoto.gx@renesas.com>
@ 2015-05-12 10:22 ` Laurent Pinchart
2015-05-13 0:08 ` Kuninori Morimoto
0 siblings, 1 reply; 2+ messages in thread
From: Laurent Pinchart @ 2015-05-12 10:22 UTC (permalink / raw)
To: Kuninori Morimoto, Mike Turquette
Cc: Ulf Hansson, Simon, linux-mmc, Magnus, Linux-SH, kobayashi,
devicetree
Hi Morimoto-san,
Thank you for the patch.
I'm CC'ing the device-tree mailing list as well as Mike Turquette, please see
below for the discussion.
On Thursday 23 April 2015 08:17:23 Kuninori Morimoto wrote:
> From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
>
> MMCIF IP on R-Car series has parent clock which can be set
> several rate, and it was not implemented on old SH-Mobile series
> (= SH-Mobile series parent clock was fixed rate)
> R-Car series MMCIF can use more high speed access if it setup
> parent clock. This patch adds parent clock setup method,
> and r8a7790/r8a7791 can use it.
>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
> ---
> v3 -> v4
>
> - add new clk-range on DT
> - use clk_round_rate() for parent_clk
> - struct sh_mmcif_ver instead of sh_mmcif_parent_clk
>
> .../devicetree/bindings/mmc/renesas,mmcif.txt | 3 +
> drivers/mmc/host/sh_mmcif.c | 89 ++++++++++++++++++-
> 2 files changed, 90 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt
> b/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt index
> 299081f..eb50f4e 100644
> --- a/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt
> +++ b/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt
> @@ -14,6 +14,8 @@ Required properties:
>
> - clocks: reference to the functional clock
>
> +- clk-range: parent clock range
> +
I think the idea of a DT property to specify the admissible range for clock
frequencies is good. However, I have a couple of small comments regarding the
implementation.
First of all, this doesn't seem Renesas-specific to me (feel free to disagree,
but in that case the property should probably be called renesas,clk-range).
Wouldn't it make sense to specify the property in
Documentation/devicetree/bindings/clock/clock-bindings.txt instead ?
Then, I think the documentation should be clarified a bit, as "parent clock
range" is probably a bit vague for people who haven't followed the development
of this patch series. How about something like "range of admissible
frequencies for the input clock" ?
There's already a clock-ranges property with a totally different meaning.
That's quite confusing, it would thus be good to rename clk-range. How about
clock-freq-range or clock-frequency-range ?
Finally, if a DT node references several clocks in its clocks property, we
need a way to specify the range for each of them.
> - dmas: reference to the DMA channels, one per channel name listed in the
> dma-names property.
> - dma-names: must contain "tx" for the transmit DMA channel and "rx" for
> the @@ -29,4 +31,5 @@ Example: R8A7790 (R-Car H2) MMCIF0
> clocks = <&mstp3_clks R8A7790_CLK_MMCIF0>;
> dmas = <&dmac0 0xd1>, <&dmac0 0xd2>;
> dma-names = "tx", "rx";
> + clk-range = <12187500 97500000>;
> };
> diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
> index d2f1158..437aa3c 100644
> --- a/drivers/mmc/host/sh_mmcif.c
> +++ b/drivers/mmc/host/sh_mmcif.c
> @@ -57,6 +57,7 @@
> #include <linux/mmc/slot-gpio.h>
> #include <linux/mod_devicetable.h>
> #include <linux/mutex.h>
> +#include <linux/of_device.h>
> #include <linux/pagemap.h>
> #include <linux/platform_device.h>
> #include <linux/pm_qos.h>
> @@ -224,6 +225,13 @@ enum mmcif_wait_for {
> MMCIF_WAIT_FOR_STOP,
> };
>
> +/*
> + * difference for each SoC
> + */
> +struct sh_mmcif_ver {
> + u32 clkdiv_map; /* see CE_CLK_CTRL::CLKDIV */
> +};
> +
> struct sh_mmcif_host {
> struct mmc_host *mmc;
> struct mmc_request *mrq;
> @@ -248,6 +256,7 @@ struct sh_mmcif_host {
> bool ccs_enable; /* Command Completion Signal support */
> bool clk_ctrl2_enable;
> struct mutex thread_lock;
> + const struct sh_mmcif_ver *ver;
>
> /* DMA support */
> struct dma_chan *chan_rx;
> @@ -256,8 +265,14 @@ struct sh_mmcif_host {
> bool dma_active;
> };
>
> +static const struct sh_mmcif_ver sh_mmcif_gen2 = {
> + .clkdiv_map = 0x3ff,
> +};
> +
> static const struct of_device_id mmcif_of_match[] = {
> { .compatible = "renesas,sh-mmcif" },
> + { .compatible = "renesas,mmcif-r8a7790", .data = &sh_mmcif_gen2},
> + { .compatible = "renesas,mmcif-r8a7791", .data = &sh_mmcif_gen2},
> { }
> };
> MODULE_DEVICE_TABLE(of, mmcif_of_match);
> @@ -490,12 +505,50 @@ static void sh_mmcif_clock_control(struct
> sh_mmcif_host *host, unsigned int clk)
>
> if (!clk)
> return;
> - if (sup_pclk && clk == current_clk)
> +
> + if (host->ver) {
> + const struct sh_mmcif_ver *ver = host->ver;
> + unsigned int freq, best_freq, myclk, clkdiv, div, diff_min, diff;
> + int i;
> +
> + clkdiv = 0;
> + diff_min = ~0;
> + best_freq = 0;
> + for (i = fls(ver->clkdiv_map); i >= 0; i--) {
> + if (!((1 << i) & ver->clkdiv_map))
> + continue;
> +
> + /*
> + * clk = parent_freq / div
> + * -> parent_freq = clk x div
> + */
> +
> + div = 1 << (i + 1);
> + freq = clk_round_rate(host->clk, clk * div);
> + myclk = freq / div;
> + diff = (myclk > clk) ? myclk - clk : clk - myclk;
> +
> + if (diff <= diff_min) {
> + best_freq = freq;
> + clkdiv = i;
> + diff_min = diff;
> + }
> + }
> +
> + dev_dbg(&host->pd->dev, "clk %u/%u (%u, 0x%x)\n",
> + (best_freq / (1 << (clkdiv + 1))), clk,
> + best_freq, clkdiv);
> +
> + clk_set_rate(host->clk, best_freq);
> + sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL,
> + CLK_CLEAR & (clkdiv << 16));
> + } else if (sup_pclk && clk == current_clk) {
> sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_SUP_PCLK);
> - else
> + } else {
> sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_CLEAR &
> ((fls(DIV_ROUND_UP(current_clk,
> clk) - 1) - 1) << 16));
> + }
>
> sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_ENABLE);
> }
> @@ -980,10 +1033,42 @@ static void sh_mmcif_request(struct mmc_host *mmc,
> struct mmc_request *mrq)
>
> static void sh_mmcif_clk_setup(struct sh_mmcif_host *host)
> {
> + struct device *dev = &host->pd->dev;
> + const struct of_device_id *of_id = of_match_device(mmcif_of_match, dev);
> unsigned int clk = clk_get_rate(host->clk);
>
> + if (of_id) {
> + struct device_node *np = dev->of_node;
> + const struct sh_mmcif_ver *ver = of_id->data;
> + u32 range[2]; /* min/max */
> +
> + if (!ver)
> + goto sh_mmcif_clk_setup_default;
> +
> + if (0 != of_property_read_u32_array(np, "clk-range",
> + range, ARRAY_SIZE(range)))
> + goto sh_mmcif_clk_setup_default;
> +
> + if (range[0] > range[1])
> + goto sh_mmcif_clk_setup_default;
> +
> + host->mmc->f_min = range[0] / (1 << fls(ver->clkdiv_map));
> + host->mmc->f_max = range[1] / (1 << ffs(ver->clkdiv_map));
> +
> + dev_dbg(dev, "parent clk <%d - %d> (%d/%d)\n",
> + range[0], range[1],
> + host->mmc->f_max, host->mmc->f_min);
> +
> + host->ver = ver;
> + return;
> + }
> +
> +sh_mmcif_clk_setup_default:
> host->mmc->f_max = clk / 2;
> host->mmc->f_min = clk / 512;
> +
> + dev_dbg(dev, "clk max/min = %d/%d\n",
> + host->mmc->f_max, host->mmc->f_min);
> }
>
> static void sh_mmcif_set_power(struct sh_mmcif_host *host, struct mmc_ios
> *ios)
--
Regards,
Laurent Pinchart
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