RE: [PATCH 2/8] mmc: sdhci: host: add new f_sdh30

Vincent.Yang
2014-07-16T09:35:41Z

>-----Original Message-----
>From: Arnd Bergmann [mailto:arnd@arndb.de]
>On Sunday 13 July 2014 14:29:31 Mollie Wu wrote:
>> +Required properties:
>> +- compatible: "fujitsu,f-sdh30"
>> +- voltage-ranges : This is a list of pairs. In each pair, two cells
>> + are required. First cell specifies minimum slot voltage (mV), second
>> + cell specifies maximum slot voltage (mV). In case of supported voltage
>> + range is discontinuous, several ranges could be specified as a list.
>> +
>> +Optional properties:
>> +- pwr-mux-gpios: This is one optional gpio for controlling a power mux
>> + which switches between two power supplies. 3.3V is selected when gpio
>> + is high, and 1.8V is selected when gpio is low. This voltage is used
>> + for signal level.
>
>It sounds like what you really want here is a reference to a gpio-regulator
>node and, and to put the details of the voltage switching in there.

Hi Arnd,
Yes, I'll use a gpio-regulator for it in next version.

>
>> diff --git a/drivers/mmc/host/sdhci_f_sdh30.c
>b/drivers/mmc/host/sdhci_f_sdh30.c
>> new file mode 100644
>> index 0000000..8d23f2d
>> --- /dev/null
>> +++ b/drivers/mmc/host/sdhci_f_sdh30.c
>> @@ -0,0 +1,380 @@
>> +/*
>> + * linux/drivers/mmc/host/sdhci_f_sdh30.c
>> + *
>> + * Copyright (C) 2013 - 2014 Fujitsu Semiconductor, Ltd
>> + * Vincent Yang <vincent.yang@tw.fujitsu.com>
>> + * Copyright (C) 2014 Linaro Ltd Andy Green <andy.green@linaro.org>
>> + *
>> + * This program is free software: you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation, version 2 of the License.
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/delay.h>
>> +#include <linux/module.h>
>> +#include <linux/mmc/sd.h>
>> +#include <linux/mmc/host.h>
>> +#include <linux/mmc/card.h>
>> +#include <linux/gpio.h>
>> +#include <linux/of_gpio.h>
>> +#include <linux/of_address.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/suspend.h>
>> +
>> +#include "sdhci.h"
>> +#include "sdhci-pltfm.h"
>> +#include "../core/core.h"
>
>Should this be <linux/mmc/core.h>? A device driver should not be looking
>at the drivers/mmc/core/core.h.

Yes, I'll remove it.

>
>> +#define DRIVER_NAME "f_sdh30"
>
>This macro doesn't seem to serve any purpose, it would be easier to
>read if you open-code this.

Yes, I'll do it.

>
>> +
>> +void sdhci_f_sdh30_soft_voltage_switch(struct sdhci_host *host)
>> +{
>> + struct f_sdhost_priv *priv = sdhci_priv(host);
>> + u32 ctrl = 0;
>> +
>> + usleep_range(2500, 3000);
>> + ctrl = sdhci_readl(host, F_SDH30_IO_CONTROL2);
>> + ctrl |= F_SDH30_CRES_O_DN;
>> + sdhci_writel(host, ctrl, F_SDH30_IO_CONTROL2);
>> + ctrl |= F_SDH30_MSEL_O_1_8;
>> + sdhci_writel(host, ctrl, F_SDH30_IO_CONTROL2);
>> +
>> + if (gpio_is_valid(priv->gpio_select_1v8)) {
>> + dev_info(priv->dev, "%s: setting gpio\n", __func__);
>> + gpio_direction_output(priv->gpio_select_1v8, 0);
>> + }
>> +
>> + ctrl &= ~F_SDH30_CRES_O_DN;
>> + sdhci_writel(host, ctrl, F_SDH30_IO_CONTROL2);
>> + usleep_range(2500, 3000);
>> +
>> + if (priv->vendor_hs200) {
>> + dev_info(priv->dev, "%s: setting hs200\n", __func__);
>> + ctrl = sdhci_readl(host, F_SDH30_ESD_CONTROL);
>> + ctrl |= priv->vendor_hs200;
>> + sdhci_writel(host, ctrl, F_SDH30_ESD_CONTROL);
>> + }
>> +
>> + ctrl = sdhci_readl(host, F_SDH30_TUNING_SETTING);
>> + ctrl |= F_SDH30_CMD_CHK_DIS;
>> + sdhci_writel(host, ctrl, F_SDH30_TUNING_SETTING);
>> +}
>
>I think this should really use the regulator API.
>
>If the regular is defined properly, this will work without any extra code.

Yes, I'll use a gpio-regulator for it.

>
>> +unsigned int sdhci_f_sdh30_get_min_clock(struct sdhci_host *host)
>> +{
>> + return F_SDH30_MIN_CLOCK;
>> +}
>> +
>> +void sdhci_f_sdh30_reset(struct sdhci_host *host, u8 mask)
>> +{
>> + struct f_sdhost_priv *priv = sdhci_priv(host);
>> +
>> + if (gpio_is_valid(priv->gpio_select_1v8))
>> + gpio_direction_output(priv->gpio_select_1v8, 1);
>> +
>> + if (sdhci_readw(host, SDHCI_CLOCK_CONTROL) == 0) {
>> + sdhci_writew(host, 0xBC01, SDHCI_CLOCK_CONTROL);
>> + mmiowb();
>> + }
>
>Can you explain the mmiowb call here?

This came from the original 3.0 based driver. It's trying to be a
write memory barrier. It wants to ensure the clock control change
actually happened before the following code.
I'll change it to a regular wmb in next version.

>
>> +
>> + if (!of_property_read_u32(pdev->dev.of_node, "bus-width", &bus_width))
>{
>> + switch (bus_width) {
>> + case 8:
>> + dev_info(dev, "Applying 8 bit bus width\n");
>> + host->mmc->caps |= MMC_CAP_8_BIT_DATA;
>> + break;
>> + case 4:
>> + dev_info(dev, "Applying 4 bit bus width\n");
>> + host->mmc->caps |= MMC_CAP_4_BIT_DATA;
>> + break;
>> + case 1:
>> + default:
>> + dev_err(dev, "Invalid bus width: %u\n", bus_width);
>> + break;
>> + }
>> + }
>
>This should probably be done in generic sdhci code somewhere. How about
>adding it to sdhci_get_of_property instead_

I should use generic mmc_of_parse for it. I'll update it in next version.

>> + priv->clk_sd4 = clk_get(&pdev->dev, "sd_sd4clk");
>> + if (!IS_ERR(priv->clk_sd4)) {
>> + ret = clk_prepare_enable(priv->clk_sd4);
>> + if (ret < 0) {
>> + dev_err(dev, "Failed to enable sd4 clock: %d\n", ret);
>> + goto err_clk1;
>> + }
>> + }
>> + priv->clk_b = clk_get(&pdev->dev, "sd_bclk");
>> + if (!IS_ERR(priv->clk_b)) {
>> + ret = clk_prepare_enable(priv->clk_b);
>> + if (ret < 0) {
>> + dev_err(dev, "Failed to enable clk_b clock: %d\n", ret);
>> + goto err_clk2;
>> + }
>> + }
>
>Please pick clock names that match what some of the other drivers use.

I'll use "iface" and "core" for clock names because they match what used
in sdhci-msm driver.

Thanks a lot for your review!

Best regards,
Vincent Yang

>
>Ideally some of that should also move to common code.
>
> Arnd