Quoting dinguyen@xxxxxxxxxx (2013-12-16 09:04:33)
> From: Dinh Nguyen <dinguyen@xxxxxxxxxx>
>
> The clk-phase property is used to represent the 2 clock phase values that is
> needed for the SD/MMC driver. Add a prepare function to the clk_ops, that will
> use the syscon driver to set sdmmc_clk's phase shift that is located in the
> system manager.
>
> Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxx>
> ---
> v7: Add dts property to represent the clk phase of the sdmmc_clk. Add a
> prepare function to the gate clk that will toggle clock phase setting.
> Remove the "altr,socfpga-sdmmc-sdr-clk" clock type.
> v6: Add a new clock type "altr,socfpga-sdmmc-sdr-clk" that will be used to
> set the phase shift settings.
> v5: Use the "snps,dw-mshc" binding
> v4: Use the sdmmc_clk prepare function to set the phase shift settings
> v3: Not use the syscon driver because as of 3.13-rc1, the syscon driver is
> loaded after the clock driver.
> v2: Use the syscon driver
> ---
> .../devicetree/bindings/clock/altr_socfpga.txt | 14 ++++++++
> arch/arm/boot/dts/socfpga.dtsi | 1 +
> drivers/clk/socfpga/clk.c | 36 ++++++++++++++++++++
> 3 files changed, 51 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/clock/altr_socfpga.txt b/Documentation/devicetree/bindings/clock/altr_socfpga.txt
> index 0045433..4b66754 100644
> --- a/Documentation/devicetree/bindings/clock/altr_socfpga.txt
> +++ b/Documentation/devicetree/bindings/clock/altr_socfpga.txt
> @@ -23,3 +23,17 @@ Optional properties:
> and the bit index.
> - div-reg : For "socfpga-gate-clk", div-reg contains the divider register, bit shift,
> and width.
> +- clk-phase : For the sdmmc_clk, contains the value of the clock phase that controls
> + the SDMMC CIU clock. The first value is the clk_sample(smpsel), and the second
> + value is the cclk_in_drv(drvsel). The clk-phase is used to enable the correct
> + hold/delay times that is needed for the SD/MMC CIU clock. The values of both
> + value can be one of the following:
> +
> + <0x0> : 0 degrees
> + <0x1> : 45 degrees
> + <0x2> : 90 degrees
> + <0x3> : 135 degrees
> + <0x4> : 180 degrees
> + <0x5> : 225 degrees
> + <0x6> : 270 degrees
> + <0x7> : 315 degrees
> diff --git a/arch/arm/boot/dts/socfpga.dtsi b/arch/arm/boot/dts/socfpga.dtsi
> index f936476..616d9ee 100644
> --- a/arch/arm/boot/dts/socfpga.dtsi
> +++ b/arch/arm/boot/dts/socfpga.dtsi
> @@ -413,6 +413,7 @@
> compatible = "altr,socfpga-gate-clk";
> clocks = <&f2s_periph_ref_clk>, <&main_nand_sdmmc_clk>, <&per_nand_mmc_clk>;
> clk-gate = <0xa0 8>;
> + clk-phase = <0 3>;
Looking at this again, I have a hard time understanding the values in
the clk-phase property. You reference some functions in the property
definition above, but they are not obvious to me.
Additionally I wonder if the binding would better if the clock-phase
property was simply the value in degrees. E.g:
clk-phase = <315>; // 315 degrees
Regards,
Mike
> };
>
> nand_x_clk: nand_x_clk {
> diff --git a/drivers/clk/socfpga/clk.c b/drivers/clk/socfpga/clk.c
> index 280c983..7cfebd6 100644
> --- a/drivers/clk/socfpga/clk.c
> +++ b/drivers/clk/socfpga/clk.c
> @@ -21,8 +21,10 @@
> #include <linux/clkdev.h>
> #include <linux/clk-provider.h>
> #include <linux/io.h>
> +#include <linux/mfd/syscon.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> +#include <linux/regmap.h>
>
> /* Clock Manager offsets */
> #define CLKMGR_CTRL 0x0
> @@ -56,6 +58,11 @@
> #define div_mask(width) ((1 << (width)) - 1)
> #define streq(a, b) (strcmp((a), (b)) == 0)
>
> +/* SDMMC Group for System Manager defines */
> +#define SYSMGR_SDMMCGRP_CTRL_OFFSET 0x108
> +#define SYSMGR_SDMMC_CTRL_SET(smplsel, drvsel) \
> + ((((smplsel) & 0x7) << 3) | (((drvsel) & 0x7) << 0))
> +
> static void __iomem *clk_mgr_base_addr;
>
> struct socfpga_clk {
> @@ -66,6 +73,7 @@ struct socfpga_clk {
> void __iomem *div_reg;
> u32 width; /* only valid if div_reg != 0 */
> u32 shift; /* only valid if div_reg != 0 */
> + u32 clk_phase[2];
> };
> #define to_socfpga_clk(p) container_of(p, struct socfpga_clk, hw.hw)
>
> @@ -243,7 +251,28 @@ static unsigned long socfpga_clk_recalc_rate(struct clk_hw *hwclk,
> return parent_rate / div;
> }
>
> +static int socfpga_clk_prepare(struct clk_hw *hwclk)
> +{
> + struct socfpga_clk *socfpgaclk = to_socfpga_clk(hwclk);
> + struct regmap *sys_mgr_base_addr;
> + u32 hs_timing;
> +
> + if (socfpgaclk->clk_phase[0] || socfpgaclk->clk_phase[1]) {
> + sys_mgr_base_addr = syscon_regmap_lookup_by_compatible("altr,sys-mgr");
> + if (IS_ERR(sys_mgr_base_addr)) {
> + pr_err("%s: failed to find altr,sys-mgr regmap!\n", __func__);
> + return -EINVAL;
> + }
> + hs_timing = SYSMGR_SDMMC_CTRL_SET(socfpgaclk->clk_phase[0],
> + socfpgaclk->clk_phase[1]);
> + regmap_write(sys_mgr_base_addr, SYSMGR_SDMMCGRP_CTRL_OFFSET,
> + hs_timing);
> + }
> + return 0;
> +}
> +
> static struct clk_ops gateclk_ops = {
> + .prepare = socfpga_clk_prepare,
> .recalc_rate = socfpga_clk_recalc_rate,
> .get_parent = socfpga_clk_get_parent,
> .set_parent = socfpga_clk_set_parent,
> @@ -254,6 +283,7 @@ static void __init socfpga_gate_clk_init(struct device_node *node,
> {
> u32 clk_gate[2];
> u32 div_reg[3];
> + u32 clk_phase[2];
> u32 fixed_div;
> struct clk *clk;
> struct socfpga_clk *socfpga_clk;
> @@ -294,6 +324,12 @@ static void __init socfpga_gate_clk_init(struct device_node *node,
> socfpga_clk->div_reg = 0;
> }
>
> + rc = of_property_read_u32_array(node, "clk-phase", clk_phase, 2);
> + if (!rc) {
> + socfpga_clk->clk_phase[0] = clk_phase[0];
> + socfpga_clk->clk_phase[1] = clk_phase[1];
> + }
> +
> of_property_read_string(node, "clock-output-names", &clk_name);
>
> init.name = clk_name;
> --
> 1.7.9.5
>
>
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