diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-bcm2835.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-bcm2835.c | 135 |
1 files changed, 113 insertions, 22 deletions
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index d2fbb4bb4a43..67752f7b0371 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -4,6 +4,8 @@ */ #include <linux/clk.h> +#include <linux/clkdev.h> +#include <linux/clk-provider.h> #include <linux/completion.h> #include <linux/err.h> #include <linux/i2c.h> @@ -51,9 +53,7 @@ struct bcm2835_i2c_dev { struct device *dev; void __iomem *regs; - struct clk *clk; int irq; - u32 bus_clk_rate; struct i2c_adapter adapter; struct completion completion; struct i2c_msg *curr_msg; @@ -74,12 +74,17 @@ static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) return readl(i2c_dev->regs + reg); } -static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev) +#define to_clk_bcm2835_i2c(_hw) container_of(_hw, struct clk_bcm2835_i2c, hw) +struct clk_bcm2835_i2c { + struct clk_hw hw; + struct bcm2835_i2c_dev *i2c_dev; +}; + +static int clk_bcm2835_i2c_calc_divider(unsigned long rate, + unsigned long parent_rate) { - u32 divider, redl, fedl; + u32 divider = DIV_ROUND_UP(parent_rate, rate); - divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), - i2c_dev->bus_clk_rate); /* * Per the datasheet, the register is always interpreted as an even * number, by rounding down. In other words, the LSB is ignored. So, @@ -88,12 +93,23 @@ static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev) if (divider & 1) divider++; if ((divider < BCM2835_I2C_CDIV_MIN) || - (divider > BCM2835_I2C_CDIV_MAX)) { - dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n"); + (divider > BCM2835_I2C_CDIV_MAX)) return -EINVAL; - } - bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); + return divider; +} + +static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw); + u32 redl, fedl; + u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate); + + if (divider == -EINVAL) + return -EINVAL; + + bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DIV, divider); /* * Number of core clocks to wait after falling edge before @@ -108,12 +124,65 @@ static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev) */ redl = max(divider / 4, 1u); - bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DEL, + bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL, (fedl << BCM2835_I2C_FEDL_SHIFT) | (redl << BCM2835_I2C_REDL_SHIFT)); return 0; } +static long clk_bcm2835_i2c_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + u32 divider = clk_bcm2835_i2c_calc_divider(rate, *parent_rate); + + return DIV_ROUND_UP(*parent_rate, divider); +} + +static unsigned long clk_bcm2835_i2c_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw); + u32 divider = bcm2835_i2c_readl(div->i2c_dev, BCM2835_I2C_DIV); + + return DIV_ROUND_UP(parent_rate, divider); +} + +static const struct clk_ops clk_bcm2835_i2c_ops = { + .set_rate = clk_bcm2835_i2c_set_rate, + .round_rate = clk_bcm2835_i2c_round_rate, + .recalc_rate = clk_bcm2835_i2c_recalc_rate, +}; + +static struct clk *bcm2835_i2c_register_div(struct device *dev, + struct clk *mclk, + struct bcm2835_i2c_dev *i2c_dev) +{ + struct clk_init_data init; + struct clk_bcm2835_i2c *priv; + char name[32]; + const char *mclk_name; + + snprintf(name, sizeof(name), "%s_div", dev_name(dev)); + + mclk_name = __clk_get_name(mclk); + + init.ops = &clk_bcm2835_i2c_ops; + init.name = name; + init.parent_names = (const char* []) { mclk_name }; + init.num_parents = 1; + init.flags = 0; + + priv = devm_kzalloc(dev, sizeof(struct clk_bcm2835_i2c), GFP_KERNEL); + if (priv == NULL) + return ERR_PTR(-ENOMEM); + + priv->hw.init = &init; + priv->i2c_dev = i2c_dev; + + clk_hw_register_clkdev(&priv->hw, "div", dev_name(dev)); + return devm_clk_register(dev, &priv->hw); +} + static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) { u32 val; @@ -271,7 +340,7 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], { struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); unsigned long time_left; - int i, ret; + int i; for (i = 0; i < (num - 1); i++) if (msgs[i].flags & I2C_M_RD) { @@ -280,10 +349,6 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], return -EOPNOTSUPP; } - ret = bcm2835_i2c_set_divider(i2c_dev); - if (ret) - return ret; - i2c_dev->curr_msg = msgs; i2c_dev->num_msgs = num; reinit_completion(&i2c_dev->completion); @@ -338,6 +403,9 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) struct resource *mem, *irq; int ret; struct i2c_adapter *adap; + struct clk *bus_clk; + struct clk *mclk; + u32 bus_clk_rate; i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); if (!i2c_dev) @@ -351,19 +419,38 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) if (IS_ERR(i2c_dev->regs)) return PTR_ERR(i2c_dev->regs); - i2c_dev->clk = devm_clk_get(&pdev->dev, NULL); - if (IS_ERR(i2c_dev->clk)) { - if (PTR_ERR(i2c_dev->clk) != -EPROBE_DEFER) + mclk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(mclk)) { + if (PTR_ERR(mclk) != -EPROBE_DEFER) dev_err(&pdev->dev, "Could not get clock\n"); - return PTR_ERR(i2c_dev->clk); + return PTR_ERR(mclk); + } + + bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev); + + if (IS_ERR(bus_clk)) { + dev_err(&pdev->dev, "Could not register clock\n"); + return PTR_ERR(bus_clk); } ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", - &i2c_dev->bus_clk_rate); + &bus_clk_rate); if (ret < 0) { dev_warn(&pdev->dev, "Could not read clock-frequency property\n"); - i2c_dev->bus_clk_rate = 100000; + bus_clk_rate = 100000; + } + + ret = clk_set_rate_exclusive(bus_clk, bus_clk_rate); + if (ret < 0) { + dev_err(&pdev->dev, "Could not set clock frequency\n"); + return ret; + } + + ret = clk_prepare_enable(bus_clk); + if (ret) { + dev_err(&pdev->dev, "Couldn't prepare clock"); + return ret; } irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); @@ -402,6 +489,10 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) static int bcm2835_i2c_remove(struct platform_device *pdev) { struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev); + struct clk *bus_clk = devm_clk_get(i2c_dev->dev, "div"); + + clk_rate_exclusive_put(bus_clk); + clk_disable_unprepare(bus_clk); free_irq(i2c_dev->irq, i2c_dev); i2c_del_adapter(&i2c_dev->adapter); |